RFR: 8316451: 6 java/lang/instrument/PremainClass tests ignore VM flags

[Leonid Mesnik]

Tests updated to use jtreg vm flags.
Tested by running tests with different flags and tier1.

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Commit messages:
 - 8316451

Changes: https://git.openjdk.org/jdk/pull/17781/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=17781&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8316451
  Stats: 10 lines in 2 files changed: 0 ins; 4 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/17781.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/17781/head:pull/17781

PR: https://git.openjdk.org/jdk/pull/17781