RFR: 8377665: JFR: Symbol table not setup for early class unloading

[Markus Grönlund]

This is a second attempt for [29672](https://github.com/openjdk/jdk/pull/29672).

Summary (copied):

"We observe a crash when running a major GC very early, which unloads classes, calling into JFR which is not properly set up for class unloading this early. A simple fix for this is to move the creation of the symbol table to the early setup of JFR, which allows us to successfully call JfrCheckpointManager::on_unloading_classes()."

Thanks to @jsikstro for reporting and investigating this issue.

Testing: jdk_jfr

Markus

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Commit messages:
 - 8377665

Changes: https://git.openjdk.org/jdk/pull/29784/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=29784&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8377665
  Stats: 17 lines in 3 files changed: 10 ins; 3 del; 4 mod
  Patch: https://git.openjdk.org/jdk/pull/29784.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/29784/head:pull/29784

PR: https://git.openjdk.org/jdk/pull/29784