Bug 1172021 - Docs: Remove unnecessary steps from setup instructions

These steps are already performed by puppet on provision, so don't need
to be performed again manually. They are mentioned on the "common tasks"
docs page if people need to run them again later.

docs/installation.rst

@@ -63,18 +63,6 @@ Setting up Vagrant
 Setting up a local Treeherder instance
 --------------------------------------
 
-* Initialize the master database
-
-  .. code-block:: bash
-
-     (venv)vagrant@local:~/treeherder$ ./manage.py init_master_db
-
-* Populate the database with repository data sources
-
-  .. code-block:: bash
-
-     (venv)vagrant@local:~/treeherder$ ./manage.py init_datasources
-
 * Export oauth credentials for all data source projects
 
   .. code-block:: bash