Fix a few issues in WindowDecor

This CL does the following:

1. Fix misuses of mTaskInfo in CaptionWindowDecoration because it's the
   old value at that time.
2. Reset RelayoutParams before using it so we don't pass old values.
3. Restore the test values by using the resources in test package so
   that we don't need to change the test every time we change the
   resources in prod.
4. Change loadResource() to loadDimension() and loadDimensionPixelSize()
   to avoid confusion with other type of resources. Also make them
   static just in case we need similar logic on other instances of
   Resources.
5. Moved RelayoutParams closer to RelayoutResult.

It also cleans up some commented out code.

Bug: 254658472
Test: atest WindowDecorationTests
Change-Id: I6fa1b06351c388e3ca6985e76c889f4ec5506c38