Disable flaky testBadApkOnly test.

A proper fix for the flakiness has been submitted to more recent
versions of the RollbackTest.

Bug: 139108668
Bug: 139175593

Test: atest StagedRollbackTest

Change-Id: Iad20ac3744b0cf4adf0355150ce957de2a24304c
Merged-In: Iaaa728aa58d894ba546677e8295faba2ebfc5e64