FLE creates internal GetQueryableEncryptionCountInfo requests that are not being passed serialization contexts.  If an agg request is passed in with the $tenant field, the IDL-based GetQueryableEncryptionCountInfo object takes in a NamespaceString object, but soon thereafter calls its serializer, which creates a prefixed $db because the default IDL serialization context does not contain any information regarding where the tenantId came from.

This will fail when the changes to SERVER-77723 correct how we deserialize the _nss member variables in the IDL request classes.