Fix and enable ConnOnActivityStartTest.

- Set parole duration to 0 so that it won't affect app standby test.
- Use a bound service to send commands to test app instead of broadcasts.
- Remove code to install/delete test app as it will be done as part of tests
  initialization.

Bug: 38432755
Test: forrest --extra_args='--class com.android.server.net.ConnOnActivityStartTest' \
      test FrameworksServicesTests
Change-Id: Ic6cd574a60c4449195f2c8cd4e04b9cb47f225c8
Merged-In: Ic6cd574a60c4449195f2c8cd4e04b9cb47f225c8