When adding files to an adjusted branch set up by --unlock-present, add them unlocked...

When adding files to an adjusted branch set up by --unlock-present, add them unlocked, not locked

Missed this when implementing it because of the default case catching
the new constructor. So, removed that default case to make sure
future types of adjusted branches don't make the same mistake.

Complicated by git-annex addurl --fast which adds the file whose content
is not present, so it needs to stay unlocked when on such a branch.

This commit was sponsored by Brock Spratlen on Patreon.