Re-enable ElementTest#elementIsReusedBetweenScenes

This CL removes invalid assumptions made in
elementIsReusedInSameSceneAndBetweenScenes and renames it to
elementIsReusedBetweenScenes. See b/325120420 for details.

Bug: 326021461
Bug: 325689406
Test: atest ElementTest
Flag: N/A
Change-Id: I7540b3265d501c086cd39e7e6f57309fb702abfb
Merged-In: I7540b3265d501c086cd39e7e6f57309fb702abfb