Allow setting n_jobs on tool invocation

[LukasNickel]

• It can be useful to set n_jobs indepently from the config file
• For the sklearn reconstructors this requires setting n_jobs on every model, that is attached to the reconstructor
• Fixes #2307

[maxnoe]

Maybe it also makes sense to set n_jobs=None for the models after training before pickling? So that the pickled models have n_jobs=None?

[codecov[bot]]

Codecov Report

Attention: 1 lines in your changes are missing coverage. Please review.

Comparison is base (2e1011b) 92.47% compared to head (0372d11) 92.46%.

Files	Patch %	Lines
ctapipe/tools/apply_models.py	85.71%	1 Missing :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #2430 +/- ## ========================================== - Coverage 92.47% 92.46% -0.02% ========================================== Files 234 234 Lines 19819 19868 +49 ========================================== + Hits 18327 18370 +43 - Misses 1492 1498 +6 ```

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