CI: add 1 retry

There are several reasons a CI job can fail, mostly infra issue,
openstack issue, other random issues which are not test failures and so
restarting once in case of failure should reduce the ammount of time
people are investigating these test unrelated failures. Also add
interruptibble:true to init to make it actually work for the rest of the
jobs.

.gitlab-ci.yml

@@ -17,6 +17,7 @@ stages:
     - schutzbot/save_journal.sh || true
     - schutzbot/upload_artifacts.sh
   interruptible: true
+  retry: 1
   tags:
     - terraform
   artifacts:
@@ -38,6 +39,7 @@ stages:
 
 init:
   stage: init
+  interruptible: true
   tags:
     - shell
   script: