RFR: 8361192: Test java/awt/Mixing/AWT_Mixing/JSplitPaneOverlapping.java fails on all platforms

[Khalid Boulanouare]

Changes heavyweight color to white, for the test to pass.

-------------

Depends on: https://git.openjdk.org/jdk/pull/25971

Commit messages:
 - Removes test from Problem List
 - Sets heavyweight background and foreground colors different than the back frame color

Changes: https://git.openjdk.org/jdk/pull/26167/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=26167&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8361192
  Stats: 3 lines in 2 files changed: 2 ins; 1 del; 0 mod
  Patch: https://git.openjdk.org/jdk/pull/26167.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/26167/head:pull/26167

PR: https://git.openjdk.org/jdk/pull/26167