When a $lookup query is issued involving a QE encrypted collection and an unencrypted collection, the implicit encrypted db client incorrectly assumes that it can only either have FLE1 or FLE2 schemas. This is not the case, as unencrypted collections provide empty schemas in CSFLE format. 

The issue is related to https://jira.mongodb.org/browse/SERVER-100260, but is currently blocking testing being performed by the crypto team.

As part of this ticket, introduce a small workaround fix in the meantime that gives priority to FLE2 schemas and ignores empty csfle schemas in determining how to generate the query to be sent to query analysis.