Update MockIme to not clear suggestions when onStartInput is called

* this is no longer needed per
  I6fd5d294cf8676a24b8576ea554824608672ce49
* also fix a potential NPE that's revealed by the same patch

Test: atest CtsInputMethodTestCases
Bug: 157515522

Change-Id: I3549d7508132ab6ee1215388d4f7d6e9a14946b1
1 file changed