ops: set default interval for stat collection to 5 seconds

When polling the NodeJS server for operations data every 10 seconds, the
data become coarse-looking when viewing it at fine-grain detail. If you
aggregate the data into a date histogram and the bucket size is 10
seconds, then there'll be missing data in every other bucket. That is,
unless the time bounds of the buckets line up PERFECTLY with the time
that operations data was collected, which is unlikely

config/kibana.yml

@@ -88,5 +88,5 @@
 # logging.verbose: false
 
 # Set the interval in milliseconds to sample system and process performance
-# metrics. Minimum is 100ms. Defaults to 10000.
-# ops.interval: 10000
+# metrics. Minimum is 100ms. Defaults to 5000.
+# ops.interval: 5000

docs/kibana-yml.asciidoc

@@ -42,7 +42,7 @@ retrying.
 error messages.
 `logging.verbose`:: *Default: false* Set the value of this setting to `true` to log all events, including system usage 
 information and all requests.
-`ops.interval`:: *Default: 10000* Set the interval in milliseconds to sample system and process performance metrics. 
+`ops.interval`:: *Default: 5000* Set the interval in milliseconds to sample system and process performance metrics.
 The minimum value is 100.
 `status.allowAnonymous`:: *Default: false* If authentication is enabled, setting this to `true` allows
 unauthenticated users to access the Kibana server status API and status page.

src/server/config/schema.js

@@ -86,7 +86,7 @@ module.exports = () => Joi.object({
   .default(),
 
   ops: Joi.object({
-    interval: Joi.number().default(10000),
+    interval: Joi.number().default(5000),
   }),
 
   plugins: Joi.object({