Disable optimize startInput in IMMS

Disable optimize start input for P since there are few corner cases that
are not been fully adressed. One solution could be to call finishInput() on every
window focusing-out in bug 9216494

Change-Id: I4deb0a5e5e2ba951ec551e399636736dc0208154
Fixes: 76078731
Bug: 37617707
Test: atest CtsInputMethodTestCases