FLE2 does updates to side collections ESC and ECOC on an encrypted insert so it can't be handled solely at the mongod level. We need to call processFLEBatch in the BulkWrite mongos code so they can create an internal transaction accordingly and handle the insert/delete/update.

• mongos should fail any bulkWrite with more than 1 namespace if there is a encryptionInformation in one of the attached nsInfo entry.
• If there is a single namespace and it has encryptionInformation, then it should delegate to processFLEBatch instead of normal code path.
• The limitation of SERVER-72768/SERVER-72769 (a single update op or a single delete op or N insert ops) also applies here.