Improve random seed processing for SMC sampling

[juanitorduz]

What is this PR about?

Closes: #6258

Checklist

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[codecov]

Codecov Report

Merging #6298 (c25ab22) into main (5d7283e) will decrease coverage by 14.33%.
The diff coverage is 100.00%.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #6298       +/-   ##
===========================================
- Coverage   94.12%   79.78%   -14.34%     
===========================================
  Files         111      111               
  Lines       23861    23852        -9     
===========================================
- Hits        22458    19031     -3427     
- Misses       1403     4821     +3418     

Impacted Files	Coverage Δ
pymc/smc/sampling.py	86.42% <100.00%> (+3.20%)	⬆️
pymc/tests/distributions/test_continuous.py	0.00% <0.00%> (-99.77%)	⬇️
pymc/tests/distributions/test_multivariate.py	0.00% <0.00%> (-99.46%)	⬇️
pymc/tests/distributions/test_discrete.py	0.00% <0.00%> (-98.89%)	⬇️
pymc/tests/distributions/test_distribution.py	0.00% <0.00%> (-98.17%)	⬇️
pymc/tests/distributions/util.py	43.70% <0.00%> (-47.17%)	⬇️
pymc/distributions/multivariate.py	57.77% <0.00%> (-34.51%)	⬇️
pymc/distributions/discrete.py	64.85% <0.00%> (-34.37%)	⬇️
pymc/distributions/continuous.py	65.31% <0.00%> (-32.20%)	⬇️
pymc/distributions/transforms.py	85.00% <0.00%> (-15.00%)	⬇️
... and 8 more