Deal with slow permissionMgr dump

Some devices, esp. virtual devices can take a long time to produce a
permission mgr dump. This can be longer than the timeout and hence the
test gets a null dump.

In these cases, just skip the test.

Fixes: 164441904
Test: atest PermissionControllerOutOfProcessTests
Change-Id: I58247267de192f53d7182c9c435c8507015ab8c3