[jdk17] RFR: 8268597: mark hotspot runtime/symboltable tests which ignore external VM flags

[Igor Ignatyev]

Hi all,

could you please review this small and trivial patch that adds `@requires vm.flagless` to `symboltable/ShortLivedSymbolCleanup.java` test as it ignores all external flags?

Thanks,
-- Igor

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Commit messages:
 - copyright
 - 8268597

Changes: https://git.openjdk.java.net/jdk17/pull/21/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17&pr=21&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8268597
  Stats: 2 lines in 1 file changed: 1 ins; 0 del; 1 mod
  Patch: https://git.openjdk.java.net/jdk17/pull/21.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17 pull/21/head:pull/21

PR: https://git.openjdk.java.net/jdk17/pull/21