Include stack traces from keystore2 in bugreports on debuggable builds

This is needed to debug hangs in keystore2.

Bug: 186879912
Test: 'adb bugreport', then find the stack traces for keystore2 in the
      "VM TRACES JUST NOW" section of the main bugreport file.
Change-Id: I76b591efa6a66173babe2784fdb5f472ceb840f1