refactor: cleanup shutdown hook registration method documentation

[metacosm]

• refactor: cleanup shutdown hook registration method documentation
• refactor: minor improvements

[Copilot]

Pull request overview

Cleans up the installShutdownHook API documentation by formally deprecating the Duration-based overload (whose argument is now ignored in favor of ConfigurationService#reconciliationTerminationTimeout()) and adds a Javadoc to stop(). Also makes minor refactoring improvements in LeaderElectionManager: extracting REQUIRED_VERBS as a constant, using an unmodifiable set for collected verbs, and joining missing verbs into a comma-separated string for the error message.

Changes:

• Split installShutdownHook(Duration) into a deprecated delegating overload plus a documented no-arg installShutdownHook(), and add Javadoc to stop().
• Extract REQUIRED_VERBS constant and switch verb collection to toUnmodifiableSet() in LeaderElectionManager#checkLeaseAccess.
• Format the missing-verbs portion of the OperatorException message as a comma-separated string.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated no comments.

File	Description
operator-framework-core/.../Operator.java	Deprecates installShutdownHook(Duration), adds Javadoc for new no-arg overload and stop().
operator-framework-core/.../LeaderElectionManager.java	Refactors lease access check: constant for required verbs, unmodifiable set, joined missing-verb message.

[csviri]

@metacosm feel free to merge this, thx!

[metacosm]

@metacosm feel free to merge this, thx!

OK, this will most likely create conflicts with #3383, though…

[csviri]

Will merge that, PR, please rebase this on it.