RFR: 8282420: JFR: Remove event handlers [v4]

[Erik Gahlin]

> Hi,
> 
> Could I have a review of a fix that removes event handler classes for JFR. Bytecode for event instrumentation is now only added to the event class. Benefits are:
> 
> - No class memory leak in the boot class loader.
> - Reduce overhead from class loading during startup, which is important with additional JDK events that are coming (VirtualThreadStart etc.)
> - One less frame to traverse when recording a Java stack trace.
> 
> Future benefits are:
> 
> - Simplify creating instrumentation as a build step. See https://bugs.openjdk.java.net/browse/JDK-8279354
> - Simplify implementation of Event Metrics. See https://bugs.openjdk.java.net/browse/JDK-8224749
> 
> When the Security Manager is removed, much of the code being added for security reasons can be deleted.
> 
> There are few JFR hooks when code is being linked. Plan is to also use these for other events later. 
> 
> Testing: tier 1-4, jdk/jdk/jfr
> 
> Thanks
> Erik

Erik Gahlin has updated the pull request with a new target base due to a merge or a rebase. The pull request now contains eight commits:

 - Merge
 - Typos in cleanups
 - Cleanups
 - Test cleanup
 - Test fixes
 - Fix whitespaces
 - Use EventWriterFactory
 - Initial

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Changes: https://git.openjdk.java.net/jdk/pull/8383/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=8383&range=03
  Stats: 4076 lines in 82 files changed: 2415 ins; 1050 del; 611 mod
  Patch: https://git.openjdk.java.net/jdk/pull/8383.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/8383/head:pull/8383

PR: https://git.openjdk.java.net/jdk/pull/8383