Jit backend: Fix PRNG bug during autotune

[louisfd]

During the element types refactor of #1693 some types in PRNG that really needed to be Float were accidentally replaced with the input's element type. This could cause a type mismatch in the PRNG kernel, which could happen during autotune of int/bool tensors, which call uniform distribution PRNG.

Fix #1790

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 86.40%. Comparing base (76fe0ed) to head (67a434f).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #1791   +/-   ##
=======================================
  Coverage   86.39%   86.40%           
=======================================
  Files         737      737           
  Lines       85883    85891    +8     
=======================================
+ Hits        74202    74210    +8     
  Misses      11681    11681           

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