RFR: 8335130: The test "javax/swing/plaf/synth/ComponentsOrientationSupport/5033822/bug5033822.java" fails because the background color of the tabs is displayed incorrectly.

[Abhishek Kumar]

Issue is due to the condition added for the opaque property of SynthTabbedPane in [JDK-8226990](https://bugs.openjdk.org/browse/JDK-8226990). The previous fix for GTK and Nimbus was handled commonly in `SynthTabbedPaneUI` class to render the tabs based on opaque property. Since the Synth package is responsible to create a custom L&F using user defined XML file. In this test the L&F is fetched through the XML file and when `SynthTabbedPaneUI` APIs are invoked for the tab rendering, it is not correctly rendered. Setting the opaque property to true also doesn't help as the selected tab is rendered incorrectly. The proposed fix is to move the fix to GTK and Nimbus specific class and that will not cause any impact on custom xml based L&F.

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Commit messages:
 - TabbedPane tab rendering moved to specific painter class for GTK and Nimbus L&F

Changes: https://git.openjdk.org/jdk/pull/20091/files
  Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=20091&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8335130
  Stats: 49 lines in 3 files changed: 9 ins; 8 del; 32 mod
  Patch: https://git.openjdk.org/jdk/pull/20091.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/20091/head:pull/20091

PR: https://git.openjdk.org/jdk/pull/20091