Make single metastore call to fetch all column stats instead of separate call for each column

Currently HiveRelFieldTrimmer has the ability to fetch (and trigger cache) column stats in single call.
HiveReduceExpressionsWithStatsRule on the other hand has to use column stats on demand, as a result it makes single call for each column.
This should be moved after RelFieldTrimmer so that RelFieldTrimmer has all the column stats cached.