Avoid syncing activity tables to the mirror h2 database

When some repositories get corrupted on the mirror, to resolve this it is necessary to remove the project from the mirror sync'd list and restart the mirror to delete the corrupt repository.

If the project contains many large repositories, with a lot of activity, deleting them can take hours, rendering the entire mirror unavailable.

It may help to avoid syncing activity tables, such as sta_repo_push_ref etc, to speed up the repository deletion.