Add DEFAULT dump priority for services

- Adds a new DEFAULT priority for services which is treated the same as NORMAL priority but dumpsys does not send "--dump-priority" arguments to the service.

Bug: 27429130
Test: Manually generate bugrepot (default version) and check for any issues
Test: Load bugreport on ABT
Test: mmm -j56 frameworks/native/cmds/dumpstate && \
      adb shell /data/nativetest64/dumpstate_smoke_test/dumpstate_smoke_test && \
      printf "\n\n#### ALL TESTS PASSED ####\n"

Change-Id: Ia90ae16d56d0144e679cf39ebfbf4473dd21f167