Removing extra use statements

Clearing up unused `use` statements

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets |
| License       | MIT
| Doc PR        |
Seems there no test for checking the content of this file. I've checked and 1) all tests passes on master branch 2) only place this file is referenced is the `Symfony\Bridge\ProxyManager\Tests\LazyProxy\Dumper\PhpDumperTest::testDumpContainerWithProxyServiceWillShareProxies` test where the functionality is tested. The `lazy_service_structure.txt` fixture is used to test the generation. However I feel like you have a point that the generated file should be tested although having that in a fixture means that we don't actually check that the current version of the code generated file is functional.