This commit modifies the way the `@RecordApplicationEvents` annotation
works in tests, allowing for capture of events from threads other than
the main test thread (async events) and for the assertion of captured
event from a separate thread (e.g. when using `Awaitility`).
This is done by switching the `ApplicationEventsHolder` to use an
`InheritedThreadLocal`.
There is a mutual exclusion between support of asynchronous events vs
support of JUnit5 parallel tests with the `@TestInstance(PER_CLASS)`
mode. As a result, we favor the former and now `SpringExtension` will
invalidate a test class that is annotated (or meta-annotated, or
enclosed-annotated) with `@RecordApplicationEvents` AND
`@TestInstance(PER_CLASS)` AND `@Execution(CONCURRENT)`.
See gh-29827
Closes gh-30020
b39e93d0d1