Revert two patches to fix GH58452 regression

GH58452 is a regression in the 16.0 release branch caused by both:
b8a1b698 and
3a0309c5

This patch reverts both of those to make the 'valid' code stop
diagnosing
at the expense of crashes on invalid + unclear diagnostics.

This patch also adds the tests from GH58452 to prevent any
re-application from breaking this again.

Revert "[clang] Improve diagnostics for expansion length mismatch"
This reverts commit 3a0309c5.
Revert "[clang] fix missing initialization of original number of expansions"
This reverts commit b8a1b698.

Differential Revision: https://reviews.llvm.org/D145605