Summary:
Since all development goes to `dev` branch, this sets the `arc land` to
use `dev` branch as the destination. Typing `arc land` should now behave
the same as `arc land --onto dev`
Note that "arc.land.onto.default" only takes a branch name. The name
will be prepended with remote name, which is `origin` by default. So,
the commit will land by default onto `origin/dev`.
Reviewers: buda
Reviewed By: buda
Subscribers: pullbot
Differential Revision: https://phabricator.memgraph.io/D89
