RFR: 8366558: Gtests leave /tmp/cgroups-test* files

[Arno Zeller]

The gtests leave two files on Linux in the tmp directory. This change will move the cleanup code to the end in one sub test and add a missing cleanup code in another one

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

Commit messages:
 - Ensure test_file gets remove at end of subtest.

Changes: https://git.openjdk.org/jdk/pull/27036/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=27036&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8366558
  Stats: 5 lines in 1 file changed: 4 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/27036.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/27036/head:pull/27036

PR: https://git.openjdk.org/jdk/pull/27036