change remove independent variables setting to False by default

[valentinsulzer]

Description

Been meaning to do this for a while due to hard-to-fix bugs such as #2528 . #4019 was good motivation.

To set the setting to True (which can speed up the simulation, especially during the rest period), do

pybamm.Simulation(..., discretisation_kwargs={"remove_independent_variables_from_rhs": True)

Fixes #2528

Type of change

Please add a line in the relevant section of CHANGELOG.md to document the change (include PR #) - note reverse order of PR #s. If necessary, also add to the list of breaking changes.

• New feature (non-breaking change which adds functionality)
• Optimization (back-end change that speeds up the code)
• Bug fix (non-breaking change which fixes an issue)

Key checklist:

• No style issues: $ pre-commit run (or $ nox -s pre-commit) (see CONTRIBUTING.md for how to set this up to run automatically when committing locally, in just two lines of code)
• All tests pass: $ python run-tests.py --all (or $ nox -s tests)
• The documentation builds: $ python run-tests.py --doctest (or $ nox -s doctests)

You can run integration tests, unit tests, and doctests together at once, using $ python run-tests.py --quick (or $ nox -s quick).

Further checks:

• Code is commented, particularly in hard-to-understand areas
• Tests added that prove fix is effective or that feature works

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.59%. Comparing base (61bc39b) to head (e07223d).
Report is 1 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #4020   +/-   ##
========================================
  Coverage    99.59%   99.59%           
========================================
  Files          258      258           
  Lines        21306    21310    +4     
========================================
+ Hits         21219    21223    +4     
  Misses          87       87           

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[brosaplanella]

Looks good, thanks!

[valentinsulzer]

Converted to draft as I will work on fixing coverage