Iterator Builder should handle exceeded term thresholds

[mineralntl]

Currently iterator building does not handle exceeded term markers and will fail queries. We should implement a way to convert query terms that have exceeded the system limit into Ivarators. When determining whether or not a query is executable, we should continue to mark as NON_EXEC when comparing against the global index, but EXEC when comparing against the field index.

Note: This is the long-term fix to #1560 and reverts the query marking to ERROR