RFR: 8326006: Allow TEST_VM_FLAGLESS to set flagless mode [v2]

[Leonid Mesnik]

> Allow TEST_VM_FLAGLESS to enable/disable flagless tests execution explicitly.
> Sometimes the tests are executed in the mode that is incompatible with flag-sensitive tests. This mode should be able to disable them explicitly.

Leonid Mesnik has updated the pull request incrementally with one additional commit since the last revision:

  fixed according to comments.

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

Changes:
  - all: https://git.openjdk.org/jdk/pull/17886/files
  - new: https://git.openjdk.org/jdk/pull/17886/files/65859eed..b9aeeb77

Webrevs:
 - full: https://webrevs.openjdk.org/?repo=jdk&pr=17886&range=01
 - incr: https://webrevs.openjdk.org/?repo=jdk&pr=17886&range=00-01

  Stats: 3 lines in 1 file changed: 1 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/17886.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17886/head:pull/17886

PR: https://git.openjdk.org/jdk/pull/17886