vmagent: cap consul SD wait time under nginx timeout (#515)

nginx in front of Consul closes requests at 90s. vmagent's consul SD sends blocking queries with a 525s wait, so every watch fails with a 504 and the consul job finds no targets. That leaves no puppet-host metrics (node_exporter etc.) in VictoriaMetrics.

- set `promscrape.consul.waitTime: 50s` on the main VMAgent

Reviewed-on: #515
Co-authored-by: unkin-agent <unkin-agent@unkin.net>
Co-committed-by: unkin-agent <unkin-agent@unkin.net>

apps/base/observability/vmagent.yaml

@@ -12,6 +12,8 @@ spec:
   selectAllByDefault: true
   extraArgs:
     loggerFormat: json
+    # nginx in front of Consul cuts blocking queries at 90s; default is 525s.
+    promscrape.consul.waitTime: 50s
   remoteWrite:
     - url: http://vminsert-main.observability.svc.cluster.local:8480/insert/0/prometheus/
   resources: