[hwasan][test] Rework memaccess-clobber.ll

Previously memaccess-clobber.ll relied on both legacy PM-specific things
like `-analyze` and MemoryDependenceAnalysis, which are both deprecated.

This uses MemorySSA, which is the cool new thing that a bunch of passes
have migrated to.

Differential Revision: https://reviews.llvm.org/D119393