…hetic service (nicolas-grekas)

This PR was merged into the 3.4 branch.

Discussion
----------

[DI] Trigger deprecation when setting a to-be-private synthetic service

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | yes
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | #25253
| License       | MIT
| Doc PR        | -

Commits
-------

2817576 [DI] Trigger deprecation when setting a to-be-private synthetic service

This PR was merged into the 3.4 branch.

Discussion
----------

[DependencyInjection] Add tests to #25264

| Q             | A
| ------------- | ---
| Branch?       | 3.4
| Bug fix?      | no
| New feature?  | no
| BC breaks?    | no
| Deprecations? | no
| Tests pass?   | yes
| Fixed tickets | adds tests for #25264
| License       | MIT

As asked by @nicolas-grekas in #25253 (comment), I've added a test about his PR #25264.

Commits
-------

93441c1 Add test case for #25264

* 3.4:
  SCA with Php Inspections (EA Extended)
  Add test case for #25264
  Fixed the null value exception case.
  Remove rc/beta suffix from composer.json files
  Throw an exception is expression language is not installed
  Fail as early and noisily as possible
  [Console][DI] Fail gracefully
  [FrameworkBundle] Fix visibility of a test helper
  [link] clear the cache after linking
  [DI] Trigger deprecation when setting a to-be-private synthetic service
  [link] Prevent warnings when running link with 2.7
  [Validator] ExpressionValidator should use OBJECT_TO_STRING to allow value in message
  do not eagerly filter comment lines
  [WebProfilerBundle], [TwigBundle] Fix Profiler breaking XHTML pages (Content-Type: application/xhtml+xml)

* 4.0:
  SCA with Php Inspections (EA Extended)
  Add test case for #25264
  Fixed the null value exception case.
  Remove rc/beta suffix from composer.json files
  Ensure services & aliases can be referred to with `__toString`able objects
  Throw an exception is expression language is not installed
  [DI] Cast ids to string, as done on 3.4
  Fail as early and noisily as possible
  [Console][DI] Fail gracefully
  [FrameworkBundle] Fix visibility of a test helper
  [link] clear the cache after linking
  [DI] Trigger deprecation when setting a to-be-private synthetic service
  [Intl] Correct Typehint
  [link] Prevent warnings when running link with 2.7
  [Validator] ExpressionValidator should use OBJECT_TO_STRING to allow value in message
  do not eagerly filter comment lines
  [WebProfilerBundle], [TwigBundle] Fix Profiler breaking XHTML pages (Content-Type: application/xhtml+xml)

* 4.0: (87 commits)
  [SecurityBundle] fix setLogoutOnUserChange calls for context listeners
  [SecurityBundle] add note to info text of no-op config option logout_on_user_change
  fixed tests
  fixed typo
  [DI] Register singly-implemented interfaces when doing PSR-4 discovery
  [Security] Adding a GuardAuthenticatorHandler alias
  fixed tests
  moved method to function
  marked method as being internal
  [FrameworkBundle] Fix a bug where a color tag will be shown when passing an antislash
  [DI] Fix missing unset leading to false-positive circular ref
  [DI] Fix deep-inlining of non-shared refs
  parse newlines in quoted multiline strings
  Fix collision between view properties and form fields
  Fix collision between view properties and form fields
  Disallow viewing dot-files in Profiler
  [SecurityBundle] Fix compat with HttpFoundation >=3.4
  SCA with Php Inspections (EA Extended)
  Fix for missing whitespace control modifier in form layout
  Add test case for symfony#25264
  ...

* 3.4:
  SCA with Php Inspections (EA Extended)
  Add test case for symfony#25264
  Fixed the null value exception case.
  Remove rc/beta suffix from composer.json files
  Throw an exception is expression language is not installed
  Fail as early and noisily as possible
  [Console][DI] Fail gracefully
  [FrameworkBundle] Fix visibility of a test helper
  [link] clear the cache after linking
  [DI] Trigger deprecation when setting a to-be-private synthetic service
  [link] Prevent warnings when running link with 2.7
  [Validator] ExpressionValidator should use OBJECT_TO_STRING to allow value in message
  do not eagerly filter comment lines
  [WebProfilerBundle], [TwigBundle] Fix Profiler breaking XHTML pages (Content-Type: application/xhtml+xml)

* 4.0:
  SCA with Php Inspections (EA Extended)
  Add test case for symfony#25264
  Fixed the null value exception case.
  Remove rc/beta suffix from composer.json files
  Ensure services & aliases can be referred to with `__toString`able objects
  Throw an exception is expression language is not installed
  [DI] Cast ids to string, as done on 3.4
  Fail as early and noisily as possible
  [Console][DI] Fail gracefully
  [FrameworkBundle] Fix visibility of a test helper
  [link] clear the cache after linking
  [DI] Trigger deprecation when setting a to-be-private synthetic service
  [Intl] Correct Typehint
  [link] Prevent warnings when running link with 2.7
  [Validator] ExpressionValidator should use OBJECT_TO_STRING to allow value in message
  do not eagerly filter comment lines
  [WebProfilerBundle], [TwigBundle] Fix Profiler breaking XHTML pages (Content-Type: application/xhtml+xml)