[jdk17u] RFR: 8275608: runtime/Metaspace/elastic/TestMetaspaceAllocationMT2 too slow

[Thomas Stuefe]

Small patch to reduce the runtime of elastic metaspace tests, and make runtime more predictable.

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Commit messages:
 - Backport d6d82f52d4a4fac037ee9424503f8b7f11a61c40

Changes: https://git.openjdk.java.net/jdk17u/pull/326/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk17u&pr=326&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8275608
  Stats: 43 lines in 5 files changed: 15 ins; 10 del; 18 mod
  Patch: https://git.openjdk.java.net/jdk17u/pull/326.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk17u pull/326/head:pull/326

PR: https://git.openjdk.java.net/jdk17u/pull/326