[RemoveDIs] Auto-upgrade debug intrinsics to DbgRecords (default false) (#85650)

If --load-bitcode-into-experimental-debuginfo-iterators is true then debug
intrinsics are auto-upgraded to DbgRecords (the new debug info format).

The upgrade is trivial because the two representations are semantically
identical. llvm.dbg.value with 4 operands and llvm.dbg.addr intrinsics are
upgraded in the same way as usual, but converted directly into DbgRecords
instead of debug intrinsics.