Default solver from Casadi to IDAKLU

[BradyPlanden]

Description

This PR adds the required changes for PyBaMM's switch to the IDAKLU solver as default.

This relates to PyBAMM's #4545, where the CasadiSolver's explicit sensitivity functional is planned to be depreciated.

Issue reference

Fixes # (issue-number)

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 99.22%. Comparing base (0a55c30) to head (3bc298d).
Report is 27 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff            @@
##           develop     #546   +/-   ##
========================================
  Coverage    99.22%   99.22%           
========================================
  Files           68       68           
  Lines         4922     4926    +4     
========================================
+ Hits          4884     4888    +4     
  Misses          38       38           

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[agriyakhetarpal]

Thanks, @BradyPlanden! I think we should also bump

PyBOP/pyproject.toml

Line 29 in 66cf26c

"pybamm[jax]>=24.9",

to be >=25.4.1, as pybamm-team/PyBaMM#4915 first made it to that release.