Deprecate the experimental EventsExecutor (backport #3192)

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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.

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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

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[jmachowinski]

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

[fujitatomoya]

@jmachowinski @skyegalaxy

what difference does it make if we add this deprecation?
i mean the enforcement will be on turtle-N after M (current rolling that deprecates EventsExecutor), why do we want to this deprecation warning M and L?

[mjcarroll]

Yeah, I think we were trying to pull the deprecation cycle forward a release. It would be nice to not have to carry the experimental executor into M or N, since the non-experimental version already exists?

I suppose the alternative would be to deprecate in M, remove completely in N, but I imagine that the experimental version will be effectively unmaintained from this point forward.

[mjcarroll]

This one has always been in the experimental namespace so I feel like we have more latitude here than normal.