Fix zuul reboot playbook flock location

We were using /var/run/ansible/zuul_reboot.lock to flock around this
cron job. Unfortauntely it seems /var/run/ansible does not exist so the
flock command fails. Move the file to /var/run/zuul_reboot.lock to work
around this.

Note that we want to use /var/run since it is a tmpfs which means if the
server unexpectedly reboots we'll automatically clear the lock.

Change-Id: Ib0f4a434cbbf2152722493e80b5cc7a945c1f235

playbooks/service-bridge.yaml

@@ -51,7 +51,7 @@
         minute: 1
         hour: 0
         weekday: 6
-        job: "flock -n /var/run/ansible/zuul_reboot.lock /usr/local/bin/ansible-playbook -f 20 /home/zuul/src/opendev.org/opendev/system-config/playbooks/zuul_reboot.yaml > /var/log/ansible/zuul_reboot.log 2>&1"
+        job: "flock -n /var/run/zuul_reboot.lock /usr/local/bin/ansible-playbook -f 20 /home/zuul/src/opendev.org/opendev/system-config/playbooks/zuul_reboot.yaml > /var/log/ansible/zuul_reboot.log 2>&1"
 
     - name: Rotate Zuul restart logs
       include_role:

playbooks/zuul_reboot.yaml

@@ -1,4 +1,4 @@
-# This relies on flock -n /var/run/ansible/zuul_reboot.lock to ensure
+# This relies on flock -n /var/run/zuul_reboot.lock to ensure
 # we don't run multiple copies of this playbook concurrently.
 
 # TODO: stop pulling in the hourly job if we do this