Remove weight from BiometricPromptFallbackView scrolling

Test: verified manually and with screenshot tests in upcoming CL
Bug: 445996182
Flag: android.hardware.biometrics.bp_fallback_options
Cherrypick-From: https://googleplex-android-review.googlesource.com/q/commit:810fcd331cd9b46eb923979a5250a67a90af92dc
Merged-In: Iac88d95f6e606efcce15bbbb2a8067447392a16c
Change-Id: Iac88d95f6e606efcce15bbbb2a8067447392a16c