v-m: Do not scrape/alert on Graylog

Graylog is down because Elasticsearch corrupted itself again, and this
time, I'm just not going to bother fixing it.  I practically never use
it anymore anyway, and I want to migrate to Grafana Loki, so now seems
like a good time to just get rid of it.

victoria-metrics/alerts.yml

@@ -33,13 +33,6 @@ groups:
       collectd_processes_ps_count_processes{processes=~"samba|smbd|winbindd|krb5kdc"} < 1
     for: 5m
 
-- name: Graylog
-  rules:
-  - alert: unprocessed messages
-    expr: >-
-      org_graylog2_journal_entries_uncommitted > 100
-    for: 1h
-
 - name: mdraid
   rules:
   - alert: mdraid missing disk