Reconfiguring Swift currently fails to restart containers if
configuration changes. This is because kolla_set_configs is executed in
the containers as the default swift user, which does not have permission
to access all necessary files.
This change uses the root user to execute the command instead, which
allows it to exit with the correct status of 1 if the config files
differ.
Change-Id: I2a2363c71430a7173bb5253662412ae5dba09654
5629b5aad9