Remove year from desk review join

[Damonamajor]

When looking at #80, data from the final columns were returning as NA. This appears to be the issue of a join between condo runs where a previous iteration was done in the same year. Thus, the join could be on pin and year. Removing the year from the join results in valid outputs, and the dimensions of the join remain the same. However, I don't know if year was intended to be a part of the join for another reason.

[jeancochrane]

Looks like we introduced the assessment_pin_old join in #41 to give some guidance to Valuations on new sales that we had missed in a prior "final" model run. I just checked in with @dfsnow and he says those columns aren't necessary in the desk review sheets anymore. How about we take this opportunity to remove them and the now-unnecessary assessment_pin_old code? We could either do that here, or fold the changes into #80 to minimize conflicts regarding changes to the Excel template file.