RFR: 8333813: Seviceability tests fail due to stderr containing Temporarily processing option UseNotificationThread

[Chris Plummer]

Allow warning messages such as the following to appear in stderr:

Java HotSpot(TM) 64-Bit Server VM warning: Temporarily processing option UseNotificationThread; support is scheduled for removal in 24.0

Tested by running CI tier5, which reproduced the issue.

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Commit messages:
 - Allow warning messages about obsolete flags

Changes: https://git.openjdk.org/jdk/pull/19606/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=19606&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8333813
  Stats: 6 lines in 1 file changed: 4 ins; 0 del; 2 mod
  Patch: https://git.openjdk.org/jdk/pull/19606.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/19606/head:pull/19606

PR: https://git.openjdk.org/jdk/pull/19606