Remove updateImeDisplayId

After InputMethodService migrated to WindowProviderService,
the display is initialized by getInitialDisplayId().
Therefore, we don't need updateImeDisplayId() to initialize
InputMethodService's Display anymore.

Test: atest CtsInputMethodTestCases MultiDisplaySystemDecorationTests
Bug: 149463653

Change-Id: Ia78139b5defc48c8b0354fc1e212eeb38fd71ba4