Fix MIN(x, n) and MAX(x, n) returning NULL on window aggregations

[sviscaino]

These functions have an odd behaviour when used on window aggregations. They return NULL for all rows except the first one in the window, because the heap is being cleared by popAll here, so calling output() a second time will return NULL. We add a call to recover the state of the heap after building the output array.

Test plan -
Before

After

Unit test: mvn test -Dtest=TestMinMaxNFunction + non regression mvn test -Dtest=TestMinMaxByNAggregation

== RELEASE NOTES ==

General Changes
* Fix max(x, n) and min(x, n) returning NULL on window aggregations

[kaikalur]

Please add a couple of e2e test in abstract test queries that actually tests queries in a distributed environment

[sviscaino]

Please add a couple of e2e test in abstract test queries that actually tests queries in a distributed environment

Added some e2e tests

[sviscaino]

Addressed the issues, should be good to merge