Solr: rely on built-in default metrics (#748)

Setup based on description at https://docs.datadoghq.com/integrations/solr/?tab=host

templates/agent-conf.d/solr.yaml.erb

@@ -27,68 +27,5 @@ instances:
 # List of metrics to be collected by the integration
 # Read http://docs.datadoghq.com/integrations/java/ to learn how to customize it
 init_config:
-  conf:
-    - include:
-        type: searcher
-        attribute:
-          maxDoc:
-            alias: solr.searcher.maxdoc
-            metric_type: gauge
-          numDocs:
-            alias: solr.searcher.numdocs
-            metric_type: gauge
-          warmupTime:
-            alias: solr.searcher.warmup
-            metric_type: gauge
-    - include:
-        id: org.apache.solr.search.FastLRUCache
-        attribute:
-          cumulative_lookups:
-            alias: solr.cache.lookups
-            metric_type: counter
-          cumulative_hits:
-            alias: solr.cache.hits
-            metric_type: counter
-          cumulative_inserts:
-            alias: solr.cache.inserts
-            metric_type: counter
-          cumulative_evictions:
-            alias: solr.cache.evictions
-            metric_type: counter
-    - include:
-        id: org.apache.solr.search.LRUCache
-        attribute:
-          cumulative_lookups:
-            alias: solr.cache.lookups
-            metric_type: counter
-          cumulative_hits:
-            alias: solr.cache.hits
-            metric_type: counter
-          cumulative_inserts:
-            alias: solr.cache.inserts
-            metric_type: counter
-          cumulative_evictions:
-            alias: solr.cache.evictions
-            metric_type: counter
-    - include:
-        id: org.apache.solr.handler.component.SearchHandler
-        attribute:
-          errors:
-            alias: solr.search_handler.errors
-            metric_type: counter
-          requests:
-            alias: solr.search_handler.requests
-            metric_type: counter
-          timeouts:
-            alias: solr.search_handler.timeouts
-            metric_type: counter
-          totalTime:
-            alias: solr.search_handler.time
-            metric_type: counter
-          avgTimePerRequest:
-            alias: solr.search_handler.avg_time_per_req
-            metric_type: gauge
-          avgRequestsPerSecond:
-            alias: solr.search_handler.avg_requests_per_sec
-            metric_type: gauge
-
+  is_jmx: true
+  collect_default_metrics: true