[NFC][InstrProf] Refactor InstrProfiling lowering pass (#74970)

Akin other passes - refactored the name to `InstrProfilingLoweringPass` to better communicate what it does, and split the pass part and the transformation part to avoid needing to initialize object state during `::run`.

A subsequent PR will move `InstrLowering` to the .cpp file and rename it to `InstrLowerer`.