[clang-tidy] Fix for bugprone-sizeof-expression PR57167

This addresses a change in behavior of the bugprone-sizeof-expression
checker after upstream commit 15f3cd6b, which cleaned up
ElaboratedType sugaring in the AST.  This restores (mostly) the
beahvior of the checker prior to that commit, which may or may not have
been consistent with the intent of the checker, but at least gave a
tolerable level of what users would consider false positives.

Bug: https://github.com/llvm/llvm-project/issues/57167

Reviewed By: mizvekov, aaron.ballman

Differential Revision: https://reviews.llvm.org/D131926

Change-Id: Ibe5aad77ad00977134aa7fa67efbbd6bd725fd79