Apply layout param to NotificationShelf only when needed

Before, layout params were applied even when they stayed the same, causing a requestLayout that was propagating to the NotificationStackScrollLayout and remeasuring all notifications (even if it wasn't needed).

Bug: 245268301
Bug: 243647188
Test: Manually verified in a perfetto trace that no RequestLayout was propagated to NSSL after this change from the shelf. Currently there are no ways of writing tests, but I'm working at a way to enable us to make such kind of assertions, so I'll consider adding one when possible.
Change-Id: Ib3a360e705fe49cbff6f90ada0a52171ce9a5688