Deprecate the experimental EventsExecutor (backport #3192)

[mergify]

Description

This PR adds a compile-time deprecation warning when using the experimental EventsExecutor, warning to switch to the new Callback Group Events Executor in single-threaded mode instead.

Tests which exercise the EventsExecutor have deprecation warnings disabled while it is still in the source tree.
Also replaces one usage of the old executor with the new one in rclcpp_action/test_server.cpp.

Fixes # (issue)

Is this user-facing behavior change?

Users will now get a compiler warning when using the experimental EventsExecutor in their application code

Did you use Generative AI?

Claude Opus 4.8 was used to identify spots in the codebase where the deprecation warning suppression should be introduced.

Additional Information

This ought to be backported to at least Lyrical

---

This is an automatic backport of pull request #3192 done by Mergify.

[mergify]

Cherry-pick of 5272750 has failed:

On branch mergify/bp/lyrical/pr-3192
Your branch is up to date with 'origin/lyrical'.

You are currently cherry-picking commit 5272750.
  (fix conflicts and run "git cherry-pick --continue")
  (use "git cherry-pick --skip" to skip this patch)
  (use "git cherry-pick --abort" to cancel the cherry-pick operation)

Changes to be committed:
	modified:   rclcpp/include/rclcpp/experimental/executors/events_executor/events_executor.hpp
	modified:   rclcpp/src/rclcpp/experimental/executors/events_executor/events_executor.cpp
	modified:   rclcpp/test/rclcpp/executors/executor_types.hpp
	modified:   rclcpp/test/rclcpp/executors/test_executors_warmup.cpp
	modified:   rclcpp_action/test/test_server.cpp
	modified:   rclcpp_components/src/component_container_event.cpp

Unmerged paths:
  (use "git add <file>..." to mark resolution)
	both modified:   rclcpp/test/rclcpp/executors/test_events_executor.cpp

To fix up this pull request, you can check it out locally. See documentation: https://docs.github.com/en/pull-requests/collaborating-with-pull-requests/reviewing-changes-in-pull-requests/checking-out-pull-requests-locally

[mergify]

Tick the box to add this pull request to the merge queue (same as @mergifyio queue).

• Queue this pull request

[jmachowinski]

I don't think we allow this by the rules. Might be an exception as it is experimental ?
@mjcarroll any thoughts ?