JIT: Mark replacements as dirty after setting GTF_VAR_DEATH (#88669)

JIT: Mark replacements as dirty after setting GTF_VAR_DEATH (#88669)

Physically promoted struct locals are marked as dying when their
remainder dies since all other state is stored in other locals. However,
when we do this we must also mark all replacements as stale; otherwise
a future struct use could skip writebacks and effectively introduce new
uses, invalidating the previously marked last use bit.

Fix #88616