Fix lint warnings under cts/tests/inputmethod/
This is a mechanical refactoring. There should be no change regarding
what's asserted in these IME CTS tests.
Bug: 121097452
Bug: 149926050
Test: prebuilts/checkstyle/checkstyle.py -f cts/tests/inputmethod/ \
| grep .java
Test: atest CtsInputMethodTestCases
Change-Id: I03422109c3d068534be38809bd200312fc596380