fix(WindowMagnificationAnimationController): fix the timing issue

To guarantee that we are proceeding the following actions before all animation operations are completed, we would like to add `waitForIdleSync` after the enabling/disabling magnification method call, and reset Mock object after that if needed.

Bug: 319365368
Flag: N/A
Test: atest WindowMagnificationAniamtionControllerTest
Change-Id: I9f04cb25624472905710cd37cc4f0b0f7201716a