Don't provide IME insets to the PIP window

The PIP window will be moved up to avoid overlapping with IME when IME
is showing. The time of overlapping is very short. We don't want the PIP
window to change its layout during so.

Fix: 160346523
Test: atest InsetsStateControllerTest
Change-Id: I23be3afe2913210f6ac64aa1c19aae567e539756