Cherry-pick: 'Fix test case testLockTask_exitIfNoLongerWhitelisted'

'Test case has some timing issue while checking for test lock mode removal.
Sleep has been added to avoid the issue.'

Bug: 146396674
Fixes: 158236157
Test: run cts -m CtsDevicePolicyManagerTestCases -t
      com.android.cts.devicepolicy.MixedProfileOwnerTest#testLockTask_exitIfNoLongerWhitelisted
Change-Id: I6f6852a3107ee6d7b81d8793163dd7b6fe31408a
1 file changed