Currently, when we update manifest/full.xml, it's also necessary to land a CL to update manifest-internal/external_full.xml (and vice-versa).

This makes it extra awkward to make frequent manifest changes for things like pinned repositories.

In addition, it means that anyone (like a partner) who can't submit to manifest-internal can't correctly submit manifest changes.

It would be nice if the CQ somehow auto-managed this somehow, perhaps by auto-creating CLs that mirror changes from manifest/full.xml -> manifest-internal/external_full.xml.

Any such logic needs to not break manifest testing in the CQ.