[jdk21u-dev] RFR: 8371889: Deadlock in ThrowableTracer

[Roman Kennke]

This change initializes the event configurations (known as event handlers in earlier JDKs) early, in order to avoid potential deadlocks (see [description in the issue](https://bugs.openjdk.org/browse/JDK-8371889)).

JDK 21 is the last JDK where this is relevant, that code has been completely reworked in JDK 22 (e.g. [JDK-8319374](https://bugs.openjdk.org/browse/JDK-8319374)).

Testing:
 - [x] jdk/jfr
 - [x] tier1

-------------

Commit messages:
 - 8371889: Deadlock in ThrowableTracer

Changes: https://git.openjdk.org/jdk21u-dev/pull/2483/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2483&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8371889
  Stats: 8 lines in 2 files changed: 8 ins; 0 del; 0 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2483.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2483/head:pull/2483

PR: https://git.openjdk.org/jdk21u-dev/pull/2483