[DO NOT MERGE] Reduce the likelihood of NPE in PermissionHostTests

The original failure doesn't repro on my device, but from our recent learnings
about these kind of flaky behavior, we know that scrolling to a view that's
not currently visible is often the culprit.

So this makes b/137235326 much less likely to happen, assuming it's another one
of those.

Fixes: 137235326
Test: atest android.appsecurity.cts.PermissionsHostTest#testNoResidualPermissionsOnUninstall
Change-Id: Icc4a093777e6fa40e75115788d3c80000555a778
1 file changed