Remove key filter from shared preferences listener

If multiple keys are batched in a single write, it seems like the
callback is only called once with a single key instead of once for each
key that was written. This is causing the home panel component to not be
updated correctly.

Generally remove the ability to filter by key inside the shared
preferences flow helper in order to avoid falling into this trap.

Bug: 339095997
Test: atest SelectedComponentRepositoryTest
Test: manually verified not able to reproduce home panel bug with this
fix
Flag: NONE

Change-Id: Iac85cd2a276aba7c9590fd96aa7ff74e7b36f8d3