Fix race conditions in CountQuotaTracker test

Some of the internal APIs used in the test are called without holding
lock. This causes race conditions on shared data in the object of
CountQuotaTracker. This commit fixes the race conditions by holding the
lock when calling the internal APIs of CountQuotaTracker.

Bug: 352746619
Test: CountQuotaTrackerTest passes
Flag: EXEMPT bugfix

Change-Id: Ie4419fd183a5010b6c4ead66d7c8ee6918640680