Allow starting ephemeral apps from 'am'

We previously filtered any ephemeral app if either startActivity or
queryIntentActivities was called from a non-ephemeral app. However,
the system should have access to all activities [ephemeral or not]

Bug: 33458220
Test: cts-tradefed run commandAndExit cts-dev -m CtsAppSecurityHostTestCases -t android.appsecurity.cts.EphemeralTest
Change-Id: I381862e3848b2e6f7f7b2612e9cc8977a1e132ab