Revert "Recommit "[SCEV] Look through single value PHIs." (take 3)"

Revert "Recommit "[SCEV] Look through single value PHIs." (take 3)"

This reverts commit 20d798bd47ec5191de1b2a8a031da06a04e612e1.

This commit caused crashes in some cases, see github issue #58152.
This is fixed on main, but backporting it requires multiple
nontrivial cherrypicks.

Updating llvm/test/Transforms/LoopVectorize/create-induction-resume.ll
with update_test_checks.py, so this isn't an exact automatic revert,
as that test case was added after the reverted commit.

This fixes #58152 for the release branch.