<AWT Dev> RFR: 8225116: Test OwnedWindowsLeak.java intermittently fails

[Sergey Bylokhov]

This test rarely fails in the past on some configurations but was never a problem listed, and according to the history of CI, it fails 2 times on its own this year.

There are two possible reasons for the failure:
1. At that time we had a memory leak, which was fixed.
2. The test works too fast and it was not enough time for GC to eliminate 1000 windows.

To make the future evaluation simpler I enhanced the test and make it stricter, see some comments inline.

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Commit messages:
 - Update OwnedWindowsLeak.java
 - Update OwnedWindowsLeak.java

Changes: https://git.openjdk.java.net/jdk/pull/1105/files
 Webrev: https://webrevs.openjdk.java.net/?repo=jdk&pr=1105&range=00
  Issue: https://bugs.openjdk.java.net/browse/JDK-8225116
  Stats: 26 lines in 1 file changed: 4 ins; 12 del; 10 mod
  Patch: https://git.openjdk.java.net/jdk/pull/1105.diff
  Fetch: git fetch https://git.openjdk.java.net/jdk pull/1105/head:pull/1105

PR: https://git.openjdk.java.net/jdk/pull/1105