other: migrate over process config fields to [processes]

[ClementTsang]

Description

A description of the change, what it does, and why it was made. If relevant (e.g. UI changes), please also provide screenshots/recordings:

Migrate over process config fields from the general [flags] to [processes]. Similar to #2062, this only deprecates them at the moment.

Issue

If applicable, what issue does this address?

Closes: #

Testing

If relevant, please state how this was tested (including steps):

If this change affects the program, please also indicate which platforms were tested:

• Windows
• macOS (specify version below)
• Linux (specify distro below)
• Other (specify below)

Checklist

Ensure all of these are met:

• If this PR adds or changes a dependency, please justify this in the description
• If this is a code change, areas your change affects have been linted using (cargo fmt)
• If this is a code change, your changes pass cargo clippy --all -- -D warnings
• If this is a code change, new tests were added if relevant
• If this is a code change, your changes pass cargo test
• The change has been tested to work (see above) and doesn't appear to break other things
• Documentation has been updated if needed (README.md, help menu, docs, configs, etc.)
• There are no merge conflicts
• You have reviewed your changes first
• The pull request passes the provided CI pipeline

Other

Anything else that maintainers should know about this PR:

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 62.84%. Comparing base (edc295e) to head (b30ee56).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2063      +/-   ##
==========================================
- Coverage   63.11%   62.84%   -0.27%     
==========================================
  Files         130      130              
  Lines       18616    18611       -5     
==========================================
- Hits        11749    11696      -53     
- Misses       6867     6915      +48     

Flag	Coverage Δ
macos-14	50.21% <100.00%> (+0.01%)	⬆️
ubuntu-24.04	61.81% <100.00%> (-0.27%)	⬇️
windows-2022	49.96% <100.00%> (+0.02%)	⬆️

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