[jdk21u-dev] RFR: 8348309: MultiNST tests need more debugging and timing

[Goetz Lindenmaier]

I backport this for parity with 21.0.11-oracle.
Follow up to 8328608

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Depends on: https://git.openjdk.org/jdk21u-dev/pull/2548

Commit messages:
 - 5cd4fe63768715ec7be32e248e05e611ea9b557d

Changes: https://git.openjdk.org/jdk21u-dev/pull/2549/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk21u-dev&pr=2549&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8348309
  Stats: 68 lines in 5 files changed: 19 ins; 12 del; 37 mod
  Patch: https://git.openjdk.org/jdk21u-dev/pull/2549.diff
  Fetch: git fetch https://git.openjdk.org/jdk21u-dev.git pull/2549/head:pull/2549

PR: https://git.openjdk.org/jdk21u-dev/pull/2549