Remove CutQC

[garrison]

After CutQC is deprecated (#494), we'll eventually want to remove it. I've made this issue to keep a checklist of things we'll want to remember to do at that time.

• Remove utils/conversion.py and utils/metrics.py as well
• Remove --omit="circuit_knitting/cutting/cutqc/**/*,circuit_knitting/utils/conversion.py,circuit_knitting/utils/metrics.py" from coverage command in tox.ini
• Consider removing Aer as an explicit dependency of the library (we'll move it to be under basetest in pyproject.toml) - but see caveats in the issue Make Aer an optional dependency #148 - LET'S PUNT ON THIS
• Remove cutqc and metrices from addopts line in pyproject.toml, and anything else added temporarily as part of Deprecate CutQC #527
• grep for remaining references to cplex (e.g. in the README)
• Remove the platform: linux/amd64 line from compose.yaml and change the Docker image to run on macos-latest so it tests the Docker image on ARM