Fix elk 7 {conf,env}.d sample

Neither elastic nor logstash elements were present in container_skel
while they were referenced in component_skel which is not valid for
dynamic_inventory. So attempt to generate it resulted in:
KeyError: 'elastic-logstash' here [1]

Also elaborate more on conf.env sample as per the intents of
https://review.opendev.org/c/openstack/openstack-ansible-ops/+/707849

[1] https://opendev.org/openstack/openstack-ansible/src/branch/master/osa_toolkit/generate.py#L266

Change-Id: I74a4788ff25c5ef45c064d1f8309002b1731ad7a

elk_metrics_7x/conf.d/elk.yml

@@ -1,7 +1,9 @@
 # For the puposes of this example, the kibana nodes have been added to
-# different host machines that the logging nodes. The intention here
-# is to show that the different components can scale independently of
-# one another.
+# different host machines that the logging nodes. You can also split out
+# elastic-logstash into separate containers and put elasticsearch on
+# more suited hosts. The intention here is to show that the different
+# components can scale independently of one another.
+
 kibana_hosts:
   infra01:
     ip: 172.22.8.24
@@ -18,6 +20,22 @@ elastic-logstash_hosts:
   logging03:
     ip: 172.22.8.29
 
+#elastic_hosts:
+#  elastic01:
+#    ip: 172.22.8.30
+#  elastic02:
+#    ip: 172.22.8.31
+#  elastic03:
+#    ip: 172.22.8.32
+
+#logstash_hosts:
+#  logging01:
+#    ip: 172.22.8.27
+#  logging02:
+#    ip: 172.22.8.28
+#  logging03:
+#    ip: 172.22.8.29
+
 apm-server_hosts:
   logging01:
     ip: 172.22.8.27

elk_metrics_7x/env.d/elk.yml

@@ -7,12 +7,9 @@ component_skel:
   elastic:
     belongs_to:
       - elk_all
-      - elasticsearch
-      - elasticsearch_all
   logstash:
     belongs_to:
-      - logstash
-      - logstash_all
+      - elk_all
   kibana:
     belongs_to:
       - elk_all
@@ -27,7 +24,18 @@ container_skel:
     belongs_to:
       - elastic-logstash_containers
     contains:
-      - elastic-logstash
+      - elastic
+      - logstash
+  elastic_container:
+    belongs_to:
+      - elastic_containers
+    contains:
+      - elastic
+  logstash_container:
+    belongs_to:
+      - logstash_containers
+    contains:
+      - logstash
   kibana_container:
     belongs_to:
       - kibana_containers
@@ -47,6 +55,18 @@ physical_skel:
   elastic-logstash_hosts:
     belongs_to:
       - hosts
+  elastic_containers:
+    belongs_to:
+      - all_containers
+  elastic_hosts:
+    belongs_to:
+      - hosts
+  logstash_containers:
+    belongs_to:
+      - all_containers
+  logstash_hosts:
+    belongs_to:
+      - hosts
   kibana_containers:
     belongs_to:
       - all_containers