Remove Input Screen ViewTreeObserver

[joshliebe]

Task/Issue URL: https://app.asana.com/1/137249556945/project/1200204095367872/task/1212705755390361?focus=true

Description

• Fixes a perf issue with the Samsung keyboard when deleting characters in Search Mode.

Steps to test this PR

• Go to the Input Screen
• Type in a search query
• Verify that the bottom blur updates correctly

---

Note

Refactors bottom blur updates in SearchTabFragment for the autocomplete list.

• Replace ViewTreeObserver.OnPreDrawListener with RecyclerView.OnScrollListener and a root OnGlobalLayoutListener to invalidate BottomBlurView during scroll/layout
• Store bottomBlurView and layout listener as members; remove the global layout listener in onDestroyView to prevent leaks
• Minor: add RecyclerView import

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[joshliebe]

• Remove Input Screen ViewTreeObserver #7450 👈 (View in Graphite)
• develop

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[mikescamell]

Tested on Pixel 4a and worked fine for me 👍