[llvm] [RemoveDIs][DebugInfo] Handle DPVAssigns in AssignmentTrackingLowering (PR #78980)

[Orlando Cazalet-Hyams via llvm-commits]

https://github.com/OCHyams approved this pull request.

LGTM as tests have been added to sibling patch #78982 

https://github.com/llvm/llvm-project/pull/78980