Perform single call to `aeppl.factorized_joint_logprob` when calling `model.logpt`

[ricardoV94]

For model.logpt we are calling model.datalogpt and model.varlogpt, each of which calls aeppl.factorized_joint_logprob. It should be possible to do a single call to aeppl with all the free and observed model variables, which would save quite a lot of repeated operations on the aeppl side. For some reason this was not working when we tried it in #5166 and #4887.

pymc/pymc/model.py

Line 734 in 9d4691c

logp_var = self.varlogpt + self.datalogpt