Fix dialog flicker when onDisplayChanged is received

Adds a "distrinctUntilChanged" to the pending displayId, as
onDisplayChanged was triggering it to be recomputed, and this was
causing a flicker in the dialog. This was happening only while a video
was playing.

This makes logging for each DisplayRepository flow more clear in a perfetto trace.
Also all display events are now logged.

Flag: None
Bug: 308865451
Bug: 308789093
Test: DisplayRepositoryTest
Change-Id: I87b5d97198f1ee7e7d6983481f9cccb0634a2880