Revert "Implement "flexible hybrid" split mode"

This reverts commit 199ec4a6.

Reason for revert: Revert for 25Q3-release branch only. Fixes b/422912855. Will be fixed forward in main branch.

Bug: 349828130
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:61d4924b4be73d0c043ff0ac30a4f0070ca63ea6)
Merged-In: I245732fa605d78ce68b7f4c527607aa7a0afd71c
Change-Id: I245732fa605d78ce68b7f4c527607aa7a0afd71c