RFR: 8327176: UnreferencedExecutor.java can fail on libgraal with -Xcomp

[Doug Simon]

The `java/util/concurrent/Executors/UnreferencedExecutor.java` test can fail when run on libgraal and `-Xcomp` is specified. The problem is that libgraal in `-Xcomp` temporarily causes some extra memory pressure (probably due to [JDK-8310218](https://bugs.openjdk.org/browse/JDK-8310218)) which can cause recoverable OOMEs to occur (memory is recovered when the relevant libgraal compilations complete). It also seems related to async threads used for cleaning weak references when using G1 or ZGC as I cannot reproduce the failure under `-XX:+UseSerialGC`.

Installing a global `Thread.UncaughtExceptionHandler` that ignores `OutOfMemoryError`s resolves the problem.

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Commit messages:
 - ignore recoverable OOMEs

Changes: https://git.openjdk.org/jdk/pull/18098/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=18098&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8327176
  Stats: 23 lines in 1 file changed: 23 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/18098.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/18098/head:pull/18098

PR: https://git.openjdk.org/jdk/pull/18098