Revert "Add CTS to verify IMS.onStartInput() is called once."

This reverts commit c0bd71ea57614aafaf9eb287e5e4c3f308221fec [1].

Reason for revert:
In Bug 69845539, we successfully migrated this test from host-side to
device-side [2] hence we no longer need this test in
InputMethodServiceLifecycleTest.

Also this test is a bit flaky (Bug 70538611).

 [1]: I5fd7d8a535d66b7599bb03d7192668d00e10d81c
 [2]: I90c306ec3ce15662717d3b17b833db6c2072c2ca
      e3d0c68f1bdc72f4d9ebfc08840344a1bc1bbe6f

Bug: 35599628
Change-Id: Iacc677864b111e56d0308cc85bd2a0353978aeeb
Fixes: 70538611
Test: atest CtsInputMethodServiceHostTestCases
8 files changed