Clean-up waitForToggleCommandComplete logic

- waitForToggleCommandComplete was a legacy logic to rate limit OverviewCommandHelper to avoid too many TOGGLE commands simulataneously
- As OverviewCommandHelper iterates, commands are now executed one by one and waitForToggleCommandComplete is no longer useful
- waitForToggleCommandComplete also caused a bug that when OverviewCommandHelper times out, we cancel the command completely, which causes waitForToggleCommandComplete to remain true, as a result all subsequent TOGGLE commands will be ignored

Fix: 368328461
Test: Aggressively keep tapping recents button, it should never get stuck
Test: 3 button Overview tests in presbumit
Flag: EXEMPT BUG_FIX
Change-Id: Ia9b64057ffb8ade6b964eb7f52c2fe72b9e7f77b