Improve type stability of Jacobians and Hessian, fix test scenarios

[gdalle]

CI

• Temporarily disable tests on 1.11 because JET picks up new type instabilities

DI source

• Pre-allocate products for Jacobians and Hessians during preparation, to avoid creating closures in ntuple afterwards

DIT source

• Adjust num_to_arr scenario to prevent JET errors on 1.11
• Change reference gradient and hessian for arr_to_num scenarios so that it respects the array type of x (typically GPU arrays)

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 96.77%. Comparing base (83de009) to head (d3ea722).

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #337      +/-   ##
==========================================
+ Coverage   96.75%   96.77%   +0.01%     
==========================================
  Files         101      101              
  Lines        4811     4831      +20     
==========================================
+ Hits         4655     4675      +20     
  Misses        156      156              

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