Fix Flaky test in AccessibilityMagnificationTest

testServiceConnectionDisconnected_hasNoMagnificationOverlay
is flaky due to that the window might be not added before
disabling the service.
To fix it, we need to ensure the magnification overlay is added
before disabling the service.

Bug: 222476950
Test: atest AccessibilityMagnificationTest -- --abi x86_64 \
      --retry-strategy ITERATIONS --max-testcase-run-count 20
Change-Id: I6b3b251dcd067a8743131a39ab16f972d2e8a1a3
1 file changed