Remove updateImeParent in RecentsAnimationController

As we added this workaround logic in CL[1] to updateImeParent
for fixing the IME container somehow failed to attach to app task
while swiping the app task after rotating the screen.

Since CL[2] has improved to invoke updateImeControlTarget when
windowConfiguration changed.

As the result, we can get rid of this logic in
RecentsAnimationController and remove it.

[1]: Ia6722e1cbccd7adc8aed1828265f6fa4df78df63
[2]: If5accb22340335c951b37fa29eb8c308179bf645

Bug: 184020899
Test: manual
Change-Id: I735361fc56cee899f874a7cf08c15e526ef1133f