RFR: 8314835: gtest wrappers should be marked as flagless

[Leonid Mesnik]

The gtest wrappers don't accept external vm flags and no need to run with them.

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Commit messages:
 - 8314835

Changes: https://git.openjdk.org/jdk/pull/15462/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15462&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314835
  Stats: 7 lines in 3 files changed: 6 ins; 0 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/15462.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15462/head:pull/15462

PR: https://git.openjdk.org/jdk/pull/15462