Revert "Folder: Don't blindly trigger sync on first EtagJob result"

We need to do a sync even if the etag was empty because we do not know
if this is because the etag really changed or because it was new.

Also, some part of the code rely on this fact to schedule a sync.

The fact that there is two sync with 30 sec at the beginning is not
a big problem, because we also need to do the sync the put the directory
etag in the db.

This reverts commit 1c001ee13865ceb4598c989e5308d27aead74540.