RFR: 8335684: ThreadCpuTime.java should pause like ThreadCpuTimeArray.java

[Kevin Walls]

There are two similarly names tests.
Recently:
JDK-8335124: com/sun/management/ThreadMXBean/ThreadCpuTimeArray.java failed with CPU time out of expected range
...made a simple change to try and avoid noisy test failures.  The same fix should be applied here to ThreadCpuTime.java.

Also removing an old comment about a Solaris issue.

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Commit messages:
 - 8335684: ThreadCpuTime.java should pause like ThreadCpuTimeArray.java

Changes: https://git.openjdk.org/jdk/pull/20025/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20025&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8335684
  Stats: 12 lines in 1 file changed: 2 ins; 9 del; 1 mod
  Patch: https://git.openjdk.org/jdk/pull/20025.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20025/head:pull/20025

PR: https://git.openjdk.org/jdk/pull/20025