Adds debug logging to Backlinks

- These logs would be removed from release/non-userdebug builds.
- Also, added JvmName logcatMessage to debug build as it was only
  added to release builds earlier making it difficult to use the
  function in Java.
- Made an unrelated small small logic change so that Backlinks is
  only sent when App Clips status code is success.

Bug: 300307759
Flag: com.android.systemui.app_clips_backlinks
Test: Manually verified the logcat output
Change-Id: I6fbecdbb8f26f28529c783a7d4866a4854016de1