Fix job scheduler crash due to uninstall race

It's possible to get a PACKAGE_CHANGED broadcast well after the
package has actually been uninstalled outright because of broadcast
delivery latencies.  Understand the exception that might be thrown
when asking for package info in such cases, so we don't crash the
Android runtime.

Bug 31865735

Change-Id: I69b2678f0f724fc731aa48fed7af58ce60d3c21c