* groupBy query: optional limit push down to segment scan
* make segment level limit push down configurable
* fix teamcity errors
* fix segment limit pushdown flag handling on query level config override
* use equals for comparator check
* fix sql and null handling
* fix unused imports
* handle null offset in NullableValueGroupByColumnSelectorStrategy for buffer comparator similar to RowBasedGrouperHelper.NullableRowBasedKeySerdeHelper