Properly Register TransformMetaChangeListeners

[jdkinaxis]

Fixes #6855

Changes:
in addOrReplaceTransform: properly set the index to the end of the list instead of 0 after the list.add.

in addTransformChangeListener: remove convoluted removal logic, use list.set to replace instead of list.add, properly register the listener in an else block.

in removeTransformChangeListener: remove convoluted removal logic.

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