RFR: 8359690: New test TestCPUTimeSampleThrottling still fails intermittently

[Johannes Bechberger]

This change fixes the issue by making the test independent of the system load.

Tested both with high and low load.

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Commit messages:
 - Make TestCPUTimeSampleThrottling machine load independent

Changes: https://git.openjdk.org/jdk/pull/26506/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26506&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8359690
  Stats: 15 lines in 1 file changed: 3 ins; 7 del; 5 mod
  Patch: https://git.openjdk.org/jdk/pull/26506.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26506/head:pull/26506

PR: https://git.openjdk.org/jdk/pull/26506