JIT: build pred lists before patchpoint expansion (#81196)

JIT: build pred lists before patchpoint expansion (#81196)

Move pred list building 3 phases earlier. It now happens just after
instrumentation (or importation if we're not instrumenting) and just before
expanding patchpoints.

Revise the patchpoint, indirect call, and post importer cleanup phases
to do proper pred list maintenance.

Update the flow checker to handle cases we see when we haven't yet run
the post importer cleanup.

Contributes to #80193.