scrape-collectd-configmap: Add PB

I didn't realize this playbook wasn't even in the Git repository when I
added it to `site.yml`.

This playbook manages the `scrape-collectd` ConfigMap, which is used by
Victoria Metrics to identify the hosts it should scrape to retrieve
metrics from _collectd_.

scrape-collectd-configmap.yml

@@ -0,0 +1,27 @@
+- hosts: all
+  run_once: true
+  gather_facts: false
+  become: false
+  vars:
+    scrape_config:
+    - targets: >-
+        {{ 
+          groups["collectd-prometheus"] 
+          | difference(groups["samba-dc"]) 
+          | difference(groups["kubelet"]) 
+          | sort
+        }}
+
+  tasks:
+  - name: configmap
+    delegate_to: localhost
+    kubernetes.core.k8s:
+      namespace: victoria-metrics
+      definition:
+        apiVersion: v1
+        kind: ConfigMap
+        metadata:
+          name: scrape-collectd
+        data:
+          scrape-collectd.yml: |+
+            {{ scrape_config | to_nice_yaml }}