[jdk11u-dev] RFR: 8217329: JTREG: Clean up, remove unused imports in gc folder

Tue Oct 24 14:50:46 UTC 2023

I backport this for parity with 11.0.21-oracle.

I dropped a row of files as they are not in 11. 
The rest applied clean. 
All modified tests pass.

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Commit messages:
 - Backport 2aa7590846aa6a8cba5fc4e67300bbb676961ade

Changes: https://git.openjdk.org/jdk11u-dev/pull/2214/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk11u-dev&pr=2214&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8217329
  Stats: 55 lines in 31 files changed: 0 ins; 55 del; 0 mod
  Patch: https://git.openjdk.org/jdk11u-dev/pull/2214.diff
  Fetch: git fetch https://git.openjdk.org/jdk11u-dev.git pull/2214/head:pull/2214

PR: https://git.openjdk.org/jdk11u-dev/pull/2214