mongos passes encryptionInformation from BatchedCommandRequest to shards after rewrite for explain commands

Mongos doesn't remove the encryptionInformation from a DeleteRequest or a UpdateRequest after performing the server-side rewrite like it does for all other commands. This means that the explain command is forwarded on to each shard with encryptionInformation, and the shards attempt to perform rewrites. While this is a no-op, internal distributed transactions from mongod nodes within a sharded cluster are not supported and may have unintended consequences.