Pipelines should have one source of truth

[paul0403]

Currently we have two pipeline registries:
https://github.com/PennyLaneAI/catalyst/blob/main/frontend/catalyst/pipelines.py: the frontend pipeline is used by default qjit program flow
https://github.com/PennyLaneAI/catalyst/blob/main/mlir/lib/Driver/Pipelines.cpp: the cpp pipeline is used by cli and things like having stage names in the pipeline being passed into the pipeline kwarg on qjit, e.g. in the oqd, mbqc, ppm pytests.

This seems redundant, not to mention error-prone when developing and maintaining.

With more and more custom pipelines emerging and people start thinking about pipeline organization more (e.g. #1758 ), it would be good to have pipeline registration in just one place.