vibrator: fix VTS for effects

A few issues were causing effects tests to fail:
- invalid effects were not actually invalid
- test for invalid effects improved to consider invalid effects and
  strengths separately
- test sleeps for appropriate amount of time after requesting effect to
  be performed
- logging used to diagnose issues left in place for convenience

Bug: 141828236
Test: atest VtsHalVibratorTargetTest (on device which suffers from these
  issues that cf did not hit)

Change-Id: Id220d36c27d85f068dce6b8961f705eef8dc6a4f