Improve flaky CtsSilentUpdateHostTestCases

From the failed result, the install failed because the session was
destroyed, the session destory because it was abandoned. It is
possible a timing issue the test abandon session too early. Try to
move abandon after test finished. It should improve the flaky rate.

Bug: 288337948
Test: atest CtsSilentUpdateHostTestCases --iterations 50
Change-Id: I313034c9cc48e8dc468d673411b0917b57c643df
1 file changed