Wait for workers to terminate when the Spring context closes

[AdzerKI]

What changed?

• Added WorkerFactoryLifecycle, a SmartLifecycle that shuts down a started WorkerFactory when the context stops and waits for its workers to terminate. The wait is bounded by the standard spring.lifecycle.timeout-per-shutdown-phase.
• It is not pauseable (isPauseable() returns false, Spring Framework 7): a shut down factory cannot be started again, so a paused context, such as a cached Spring TestContext one, keeps its workers running.
• The root namespace registers it as the temporalWorkerFactoryLifecycle bean, and each non-root namespace registers its own one next to its WorkerFactory.
• Removed the ContextClosedEvent branch from NonRootNamespaceEventListener. It shut down the non-root factories only when some other context closed, and did not wait.
• Added GracefulShutdownTest: an activity is still running when the context is closed, and the test checks that it has completed and the factory has terminated once close() returns.

Why?

The root WorkerFactory is shut down by its destroyMethod without waiting, and temporalWorkflowServiceStubs is destroyed right after it. Pollers and in-flight activity completions then fail with UNAVAILABLE: Channel shutdown invoked, and the running activity is cut off. Stopping the factory in the lifecycle phase lets in-flight tasks finish before any bean is destroyed.

Closes #2026. It uses the existing Spring Boot shutdown timeout property instead of adding a new one.

Breaking changes

None. Context close now waits for in-flight tasks, up to spring.lifecycle.timeout-per-shutdown-phase (30s by default).

Server PR

N/A.

Testing

./gradlew :temporal-spring-boot-autoconfigure:spotlessCheck :temporal-spring-boot-autoconfigure:test
./gradlew :temporal-spring-boot-autoconfigure:test -P edgeDepsTest -P springBoot3Test
./gradlew :temporal-spring-boot-autoconfigure:test -P edgeDepsTest -P springBoot4Test

GracefulShutdownTest fails on current main (the activity has not completed when close() returns) and passes with the change. The full module passes on Spring Boot 2, 3 and 4.

testWorkersKeepRunningWhenContextIsPausedAndRestarted pauses and restarts the context and then runs a workflow. On Spring Boot 4 it times out without isPauseable() (the restarted context has no pollers) and passes with it; on Spring Boot 2 and 3 it is skipped, as context pausing comes with Spring Framework 7. GracefulShutdownTest was run on Spring Boot 2 and 4 for this commit.