[HttpFoundation] removed obsolete request property
[Request] removed obsolete proxy setting in tests
[HttpFoundation] refactored trusted proxies tests to make them easier to understand and change
[HttpFoundation] changed the order of IP addresses returned by Request::getClientIps()
merged branch fabpot/request (PR #7734)

This PR was merged into the master branch.

Discussion
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Refactored tests of Request::getTrustedProxies()

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | n/a
| License       | MIT
| Doc PR        | n/a

This PR reorganizes the tests for the request trusted proxies as they were unreadable. In the process, I've also removed obsolete stuff and changed the order returned by `Request::getClientIps()` (not a BC break as this method was added in 2.3 -- see #7612).

Commits
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75db8eb [HttpFoundation] changed the order of IP addresses returned by Request::getClientIps()
deccb76 [HttpFoundation] refactored trusted proxies tests to make them easier to understand and change
1af9e5e [Request] removed obsolete proxy setting in tests
168b8cb [HttpFoundation] removed obsolete request property