Modify EXT-HOST and EXT-MYSQL dashboards

-Updating some metrics that lost some periods during find and replace
-Adding missed prefixes to dashboard.json for ext-host
-Adding the dashboard to the definition file for ext-host

definitions/ext-host/dashboard.json

@@ -48,7 +48,7 @@
             "nrqlQueries": [
               {
                 "accountId": 0,
-                "query": "FROM Metric SELECT latest(`system.cpu.idle`), latest(`system.cpu.system`), latest(`system.cpu.iowait`), latest(`system.cpu.user`), latest(`system.cpu.stolen`), latest(`system.cpu.guest`) SINCE 1 day ago COMPARE WITH 7 days ago TIMESERIES"
+                "query": "FROM Metric SELECT latest(`datadog.system.cpu.idle`), latest(`datadog.system.cpu.system`), latest(`datadog.system.cpu.iowait`), latest(`datadog.system.cpu.user`), latest(`datadog.system.cpu.stolen`), latest(`datadog.system.cpu.guest`) SINCE 1 day ago COMPARE WITH 7 days ago TIMESERIES"
               }
             ],
             "yAxisLeft": {

definitions/ext-host/definition.yml

@@ -13,6 +13,9 @@ synthesis:
 compositeMetrics:
   goldenMetrics:
     - golden_metrics.yml
+dashboardTemplates:
+  newRelic:
+    template: dashboard.json
 configuration:
   entityExpirationTime: DAILY
   alertable: false

definitions/ext-mysql/golden_metrics.yml

@@ -6,27 +6,27 @@ mySqlConnections:
 mySqlMaxConnections:
   title: Max Simultaneous Connections In Use (connection)
   query:
-    select: sum(datadog.mysqlnet.max_connections)
+    select: sum(datadog.mysql.net.max_connections)
 
 mySqlDataReads:
   title: MySQL Data Reads (read)
   query:
-    select: sum(datadog.mysqlinnodb.data_reads)
+    select: sum(datadog.mysql.innodb.data_reads)
 
 mySqlDataWrites:
   title: MySQL Data Writes (write)
   query:
-    select: sum(datadog.mysqlinnodb.data_writes)
+    select: sum(datadog.mysql.innodb.data_writes)
 
 mySqlFsyncLogWrites:
   title: MySQL Fsync Op Count (write)
   query:
-    select: sum(datadog.mysqlinnodb.os_log_fsyncs)
+    select: sum(datadog.mysql.innodb.os_log_fsyncs)
 
 mySqlSlowQueries:
   title: MySQL Slow Queries (query)
   query:
-    select: sum(datadog.mysqlperformance.slow_queries)
+    select: sum(datadog.mysql.performance.slow_queries)
 
 mySqlTableLocksWaitedRate:
   title: MySQL Locking Rate (per sec)
@@ -36,4 +36,4 @@ mySqlTableLocksWaitedRate:
 mySqlUserTime:
   title: CPU Time (per sec)
   query:
-    select: sum(datadog.mysqlperformance.user_time)
+    select: sum(datadog.mysql.performance.user_time)