[jdk17u] RFR: 8272783: Epsilon: Refactor tests to improve performance

[Aleksey Shipilev]

Clean backport to improve testing.

Additional testing:
 - [x] `gc/epsilon` pass faster

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

Commit messages:
 - Backport 7f80683cfeee3c069f48d5bce45fa92b2381b518

Changes: https://git.openjdk.java.net/jdk17u/pull/56/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=56&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8272783
  Stats: 408 lines in 21 files changed: 271 ins; 29 del; 108 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/56.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/56/head:pull/56

PR: https://git.openjdk.java.net/jdk17u/pull/56