Research - use new DimDates function in place of joining directly to the table

[lizbrunet]

8143

In ticket CIID-0000 Sumanth created a function to replace directly joining to rds.DimDates in the Staging-to-FactK12StudentCounts_NeglectedOrDelinquent store procedure. Research whether we need to implement that function in other Staging-to-RDS stored procedures.