Closed test java/awt/dnd/DropTargetInInternalFrameTest/DropTargetInInternalFrameTest.html times out and fails in Windows intermittently. Noticed only in Windows 11 machines.

Log:
java.lang.RuntimeException: DropTargetListener.dragEnter() not called.
at DropTargetInInternalFrameTest.start(DropTargetInInternalFrameTest.java:133)
at com.sun.javatest.regtest.agent.AppletWrapper$AppletRunnable.run(AppletWrapper.java:157)
at java.base/java.lang.Thread.run(Thread.java:833)
java.lang.RuntimeException: The test failed.
at DropTargetInInternalFrameTest.start(DropTargetInInternalFrameTest.java:143)
at com.sun.javatest.regtest.agent.AppletWrapper$AppletRunnable.run(AppletWrapper.java:157)
at java.base/java.lang.Thread.run(Thread.java:833)
STATUS:Failed.Applet thread threw exception: java.lang.RuntimeException: The test failed.

Fix:
This test verifies that dragging from one InternalFrame and a drop target in another InternalFrame functions properly.
This test fix converts an unstable applet based test to java main based test. It also updates the test to be more comprehensive with some stabilisation improvements. This test was creating noise in CI as it often fails in Windows platform, especially in Windows 11.
Testing:

Tested using mach5 20 times per platform and got all Pass.
Tested using mach5 5 times specifically on Windows 11 and got all Pass.