Repository: flutter
Issue: On Xcode 13 "flutter build ios -v" prints warning that there are multiple matching destinations
Labels: platform-ios,tool,t: xcode,P2,team-ios,triaged-ios

With Xcode 13 installed, `flutter build ios -v` warns there are multiple iOS targets:
```
$ flutter build ios  -v
...
                   ** BUILD SUCCEEDED **


                    --- xcodebuild: WARNING: Using the first of multiple matching destinations:
                    { platform:iOS, id:dvtdevice-DVTiPhonePlaceholder-iphoneos:placeholder, name:Any iOS Device }
                    { platform:iOS Simulator, id:dvtdevice-DVTiOSDeviceSimulatorPlaceholder-iphonesimulator:placeholder, name:Any iOS Simulator
                    Device }
                    { platform:iOS Simulator, id:1D5FCF87-522E-43B7-AA01-757578491DEE, OS:15.0, name:TestAdd2AppSim }
                    { platform:iOS Simulator, id:6996EFF7-2924-4561-9031-0B067C1993C2, OS:15.0, name:iPad (8th generation) }
                    { platform:iOS Simulator, id:FFCCE84F-38CE-4532-9260-DE32A9AD162E, OS:15.0, name:iPad Air (4th generation) }
                    { platform:iOS Simulator, id:D260F448-6C56-4440-B6F1-DCD60D9A415F, OS:15.0, name:iPad Pro (9.7-inch) }
                    { platform:iOS Simulator, id:F3FE571B-0B6A-4DCB-8F3A-A7DFBF80AB4A, OS:15.0, name:iPad Pro (11-inch) (2nd generation) }
                    { platform:iOS Simulator, id:F53FBBB3-E7CF-44D4-895B-E1224502E6D5, OS:15.0, name:iPad Pro (11-inch) (3rd generation) }
                    { platform:iOS Simulator, id:957B76DB-3BF1-4EDC-8A49-979E9C29C5CA, OS:12.4, name:iPad Pro (12.9-inch) }
                    { platform:iOS Simulator, id:DD9469D8-2641-43C1-9C90-E66FB901C9A7, OS:12.4, name:iPad Pro (12.9-inch) (2nd generation) }
                    { platform:iOS Simulator, id:04859A3A-62AA-4865-9173-669E06A2D5B0, OS:12.4, name:iPad Pro (12.9-inch) (3rd generation) }
                    { platform:iOS Simulator, id:EE79D7D2-8EA8-4C67-8E06-BEA665D1B044, OS:15.0, name:iPad Pro (12.9-inch) (4th generation) }
                    { platform:iOS Simulator, id:602341EF-E534-4DE1-8A7B-E6F4A86501EA, OS:15.0, name:iPad Pro (12.9-inch) (5th generation) }
                    { platform:iOS Simulator, id:C9DE2F54-C0B6-4FF2-A34C-E2B0E29F2EB7, OS:12.4, name:iPhone 5s }
                    { platform:iOS Simulator, id:F34B0CAD-75A7-41A7-BF2A-26C625535FC6, OS:12.4, name:iPhone 6 }
                    { platform:iOS Simulator, id:EBB74968-47AD-456B-BA8B-3A58BE85F302, OS:12.4, name:iPhone 6 Plus }
                    { platform:iOS Simulator, id:084ECAE7-FE00-42D9-A68E-90F3BDCC68B0, OS:12.4, name:iPhone 6s }
                    { platform:iOS Simulator, id:36DED3AA-D9B0-4BBA-9448-B3E199121CE0, OS:12.4, name:iPhone 6s Plus }
                    { platform:iOS Simulator, id:61727199-6726-4FFB-A573-9731BBA33D97, OS:12.4, name:iPhone 7 }
                    { platform:iOS Simulator, id:EEFCCF18-66FB-426A-A24B-F93FBE280701, OS:12.4, name:iPhone 7 Plus }
                    { platform:iOS Simulator, id:1FB04F3A-9F57-4640-B2F3-873286905C6B, OS:12.4, name:iPhone 8 }
                    { platform:iOS Simulator, id:E880E841-53DB-4DFA-A8F3-FF62BE6B1A98, OS:15.0, name:iPhone 8 }
                    { platform:iOS Simulator, id:E536FBE2-3229-4CD7-843C-C60C8F2B42B2, OS:12.4, name:iPhone 8 Plus }
                    { platform:iOS Simulator, id:E63058E7-1364-46C4-87F8-04399CD5A450, OS:15.0, name:iPhone 8 Plus }
                    { platform:iOS Simulator, id:93513EF9-38EC-458B-90CB-F44A445A6679, OS:15.0, name:iPhone 11 }
                    { platform:iOS Simulator, id:8C016096-1BFC-4A6C-8D36-0B68613D2F47, OS:15.0, name:iPhone 11 Pro }
                    { platform:iOS Simulator, id:BFB1792A-351D-492D-899E-B32C23B42195, OS:15.0, name:iPhone 11 Pro Max }
                    { platform:iOS Simulator, id:B2747785-28C2-405E-B4E4-B313E96EEE73, OS:15.0, name:iPhone 12 }
                    { platform:iOS Simulator, id:023833E0-FBEE-4C0C-A75F-7EDCB5A9E026, OS:15.0, name:iPhone 12 Pro }
                    { platform:iOS Simulator, id:82446409-3964-428A-8563-5AA08CAE91F0, OS:15.0, name:iPhone 12 Pro Max }
                    { platform:iOS Simulator, id:5C67E759-20F9-4D25-A03F-E1FA57EF2E48, OS:15.0, name:iPhone 12 mini }
                    { platform:iOS Simulator, id:FFFC335F-EAAC-416A-81EF-596496383CCE, OS:12.4, name:iPhone SE }
                    { platform:iOS Simulator, id:FA946A85-41AB-491F-9159-64A9BF9578E1, OS:15.0, name:iPhone SE (2nd generation) }
                    { platform:iOS Simulator, id:C9A36DF7-7034-48B5-AE15-2AA8E3F84B79, OS:12.4, name:iPhone X }
                    { platform:iOS Simulator, id:BEE28698-093D-4489-A503-B5F8CDC33B8B, OS:12.4, name:iPhone Xs }
                    { platform:iOS Simulator, id:FD60F847-4E6E-4320-8212-9B90606FA573, OS:12.4, name:iPhone Xs Max }
                    { platform:iOS Simulator, id:97114501-3851-4C01-8814-159668DBBBA9, OS:12.4, name:iPhone Xʀ }
                    { platform:iOS Simulator, id:8096AF99-4A7B-49AE-A956-5FE6AF8C07A6, OS:15.0, name:iPod touch (7th generation) }
[  +86 ms]  └─Compiling, linking and signing... (completed in 4.0s)
[        ] Xcode build done.                                            7.5s
```
The app successfully builds.

This does not reproduce on Xcode 12.  See also https://github.com/flutter/flutter/issues/86590.

```
$ flutter doctor -v
[✓] Flutter (Channel unknown, 2.4.0-5.0.pre.241, on macOS 11.4 20F71 darwin-x64, locale en-US)
    • Flutter version 2.4.0-5.0.pre.241 at /Users/magder/Projects/flutter
    • Upstream repository unknown
    • Framework revision 81b46443da (4 days ago), 2021-07-23 17:18:47 -0700
    • Engine revision 66ae7a368c
    • Dart version 2.14.0 (build 2.14.0-356.0.dev)

[✓] Xcode - develop for iOS and macOS
    • Xcode at /Users/magder/Applications/Xcode-13_beta3.app/Contents/Developer
    • Xcode 13.0, Build version 13A5192i
    • CocoaPods version 1.10.1

[✓] Connected device (5 available)
    • iPad (mobile)      • 00008027-001925360106802E                • ios            • iOS 15.0 19A5281j
    • iPhone 6s (mobile) • d83d5bc53967baa0ee18626ba87b6254b2ab5418 • ios            • iOS 13.7 17H35
    • iPhone 11 (mobile) • 93513EF9-38EC-458B-90CB-F44A445A6679     • ios            • com.apple.CoreSimulator.SimRuntime.iOS-15-0 (simulator)
    • macOS (desktop)    • macos                                    • darwin-x64     • macOS 11.4 20F71 darwin-x64
    • Chrome (web)       • chrome                                   • web-javascript • Google Chrome 92.0.4515.107

• No issues found!
```