[jdk21u-dev] RFR: 8339366: [jittester] Make it possible to generate tests without execution

[Satyen Subramaniam]

Backporting JDK-8339366: [jittester] Make it possible to generate tests without execution. Refactos jittester logic to separate generating tests with compiling and executing them. Ran GHA Sanity Checks and new tests directly. Patch is clean. Backporting for parity with Oracle.

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

Commit messages:
 - Backport 559fc711e03cf0086bea399ffb40cf294cbbb6e1

Changes: https://git.openjdk.org/jdk21u-dev/pull/2347/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2347&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8339366
  Stats: 247 lines in 7 files changed: 167 ins; 59 del; 21 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2347.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2347/head:pull/2347

PR: https://git.openjdk.org/jdk21u-dev/pull/2347