Issue 2858 casadi

[valentinsulzer]

Description

Quick fixes so that the tests pass again.
There are still lots of improvements to be made to the casadi integrator, but these are the most urgent

Work towards. #2858

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 (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
• The documentation builds: $ python run-tests.py --doctest

You can run unit and doctests together at once, using $ python run-tests.py --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

Patch coverage: 100.00% and no project coverage change.

Comparison is base (fc146e3) 99.69% compared to head (604fefe) 99.69%.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop    #2859   +/-   ##
========================================
  Coverage    99.69%   99.69%           
========================================
  Files          273      273           
  Lines        19065    19071    +6     
========================================
+ Hits         19006    19012    +6     
  Misses          59       59           

Impacted Files	Coverage Δ
pybamm/solvers/casadi_solver.py	99.66% <100.00%> (+<0.01%)	⬆️

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[brosaplanella]

Looks good, thanks!

[jsbrittain]

Looks good to me. Will take a look at the sensitivity tests separately.