Add dims to *Ordered probs variables when appropriate

[AustinRochford]

Add dims to _probs RV for ordered distributions when appropriate.

[ColCarroll]

If there's a small repro test you wanted to add, that'd be great, but this looks fine as is.

[codecov]

Codecov Report

Merging #5084 (7237947) into main (e03f5bf) will increase coverage by 0.02%.
The diff coverage is 100.00%.

@@            Coverage Diff             @@
##             main    #5084      +/-   ##
==========================================
+ Coverage   75.10%   75.12%   +0.02%     
==========================================
  Files          87       87              
  Lines       14142    14142              
==========================================
+ Hits        10621    10624       +3     
+ Misses       3521     3518       -3     

Impacted Files	Coverage Δ
pymc/distributions/discrete.py	98.01% <100.00%> (ø)
pymc/distributions/multivariate.py	71.42% <100.00%> (ø)
pymc/backends/report.py	91.60% <0.00%> (+2.09%)	⬆️