District Point Calcs: only keep teams in district
District Point Calcs: only keep teams in district

Filters out teams that don't have a DistrictTeam model present for the
given district+year. This means we won't count teams in a third
out-of-region play in an events rankings.

Fixes issue brought up in #1166

nwalters512/the-blue-alliance,nwalters512/the-blue-alliance,synth3tk/the-blue-alliance,fangeugene/the-blue-alliance,bdaroz/the-blue-alliance,bdaroz/the-blue-alliance,tsteward/the-blue-alliance,verycumbersome/the-blue-alliance,verycumbersome/the-blue-alliance,nwalters512/the-blue-alliance,nwalters512/the-blue-alliance,verycumbersome/the-blue-alliance,phil-lopreiato/the-blue-alliance,the-blue-alliance/the-blue-alliance,verycumbersome/the-blue-alliance,the-blue-alliance/the-blue-alliance,jaredhasenklein/the-blue-alliance,verycumbersome/the-blue-alliance,tsteward/the-blue-alliance,nwalters512/the-blue-alliance,synth3tk/the-blue-alliance,bdaroz/the-blue-alliance,bdaroz/the-blue-alliance,the-blue-alliance/the-blue-alliance,tsteward/the-blue-alliance,fangeugene/the-blue-alliance,tsteward/the-blue-alliance,jaredhasenklein/the-blue-alliance,fangeugene/the-blue-alliance,phil-lopreiato/the-blue-alliance,phil-lopreiato/the-blue-alliance,synth3tk/the-blue-alliance,jaredhasenklein/the-blue-alliance,the-blue-alliance/the-blue-alliance,bdaroz/the-blue-alliance,the-blue-alliance/the-blue-alliance,verycumbersome/the-blue-alliance,fangeugene/the-blue-alliance,fangeugene/the-blue-alliance,jaredhasenklein/the-blue-alliance,phil-lopreiato/the-blue-alliance,fangeugene/the-blue-alliance,tsteward/the-blue-alliance,phil-lopreiato/the-blue-alliance,jaredhasenklein/the-blue-alliance,the-blue-alliance/the-blue-alliance,jaredhasenklein/the-blue-alliance,synth3tk/the-blue-alliance,synth3tk/the-blue-alliance,phil-lopreiato/the-blue-alliance,tsteward/the-blue-alliance,synth3tk/the-blue-alliance,bdaroz/the-blue-alliance,nwalters512/the-blue-alliance