refactor random_permutations for simplicity

[ankona]

Small refactor of random_permutations to simplify code.

Notes:

• Given thatlist(product(*param_values)) was called prior to the sampling code, I assume that the permutation count is manageable.
• Since the original code used a set to identify already retrieved permutations, random.sample (sample without replacement) should work identically

[billschereriii]

LGTM, just don't forget to update the changelog

[codecov]

Codecov Report

Merging #300 (bdca186) into develop (395ffb0) will decrease coverage by 0.09%.
The diff coverage is 100.00%.

❗ Current head bdca186 differs from pull request most recent head a566c64. Consider uploading reports for the commit a566c64 to get more accurate results

Additional details and impacted files

@@             Coverage Diff             @@
##           develop     #300      +/-   ##
===========================================
- Coverage    87.87%   87.79%   -0.09%     
===========================================
  Files           59       59              
  Lines         3390     3383       -7     
===========================================
- Hits          2979     2970       -9     
- Misses         411      413       +2     

Impacted Files	Coverage Δ
smartsim/entity/strategies.py	100.00% <100.00%> (ø)

... and 1 file with indirect coverage changes