Pass size to specialized truncated dispatch

[ricardoV94]

Closes #6156

Checklist

• Explain important implementation details 👆
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Major / Breaking Changes

• ...

Bugfixes / New features

• Fix shape bug when creating a specialized TruncatedNormal via Truncated

Docs / Maintenance

• ...

[codecov]

Codecov Report

Merging #6165 (6088c26) into main (4836bc1) will increase coverage by 15.30%.
The diff coverage is 92.85%.

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #6165       +/-   ##
===========================================
+ Coverage   77.72%   93.03%   +15.30%     
===========================================
  Files          91       91               
  Lines       20780    20789        +9     
===========================================
+ Hits        16152    19341     +3189     
+ Misses       4628     1448     -3180     

Impacted Files	Coverage Δ
pymc/tests/distributions/test_truncated.py	99.48% <90.90%> (-0.52%)	⬇️
pymc/distributions/truncated.py	99.30% <100.00%> (ø)
pymc/sampling.py	82.19% <0.00%> (+0.10%)	⬆️
pymc/model.py	88.23% <0.00%> (+0.13%)	⬆️
pymc/variational/opvi.py	87.04% <0.00%> (+0.16%)	⬆️
pymc/math.py	70.04% <0.00%> (+0.48%)	⬆️
pymc/step_methods/hmc/base_hmc.py	90.55% <0.00%> (+0.78%)	⬆️
pymc/distributions/mixture.py	95.40% <0.00%> (+2.87%)	⬆️
pymc/distributions/distribution.py	95.90% <0.00%> (+4.54%)	⬆️
pymc/distributions/dist_math.py	87.42% <0.00%> (+9.14%)	⬆️
... and 8 more