deployment/alerts: fix quoting on DiskRunsOutOfSpace (#7234)

### Describe Your Changes

there's an extra `"` at the end of the dashboard url for this alert;
remove it by making the quoting consistent with other alerts in this
file.

### Checklist

The following checks are **mandatory**:

- [X] My change adheres [VictoriaMetrics contributing
guidelines](https://docs.victoriametrics.com/contributing/).

Co-authored-by: Lauri Tirkkonen <lauri@hacktheplanet.fi>
(cherry picked from commit 8fe41b2b08)

deployment/docker/alerts-cluster.yml

@@ -40,7 +40,7 @@ groups:
         labels:
           severity: critical
         annotations:
-          dashboard: http://localhost:3000/d/oS7Bi_0Wz?viewPanel=200&var-instance={{ $labels.instance }}"
+          dashboard: "http://localhost:3000/d/oS7Bi_0Wz?viewPanel=200&var-instance={{ $labels.instance }}"
           summary: "Instance {{ $labels.instance }} (job={{ $labels.job }}) will run out of disk space soon"
           description: "Disk utilisation on instance {{ $labels.instance }} is more than 80%.\n
             Having less than 20% of free disk space could cripple merges processes and overall performance.