RFR: 8273617: UninitializedDisplayModeChangeTest.java times out on macOS 12

[Prasanta Sadhukhan]

java/awt/FullScreen/UninitializedDisplayModeChangeTest/UninitializedDisplayModeChangeTest.java is timing out every time on macOS 12 even though the test passed.
Looks like the the main process waits for child process created in the test forever, making it timeout after jtreg timeout of 2min.
Modified to wait for childprocess for 30secs.

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Commit messages:
 - Merge master
 - Fix
 - 8273617: UninitializedDisplayModeChangeTest.java times out on macOS 12

Changes: https://git.openjdk.java.net/jdk/pull/5647/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=5647&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8273617
  Stats: 4 lines in 2 files changed: 1 ins; 1 del; 2 mod
  Patch: https://git.openjdk.java.net/jdk/pull/5647.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/5647/head:pull/5647

PR: https://git.openjdk.java.net/jdk/pull/5647