Reinstate MSan suppression of PR24578.

Summary:
Revert "Rollback of commit "Repress sanitization on User dtor.""

There is no point in keeping an active MSan error in the codebase.
PR24578 tracks the actual UB in LLVM code; this change enables testing
of LLVM with MSAN + -fsanitize-memory-use-after-dtor.

This reverts commit 21c1bc46.

Reviewers: vitalybuka

Subscribers: hiraditya, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D70611