Add eu-west-3 in cloudwatch datasource default's region (#10477)

* Add eu-west-3 as a possible default datasource

* Add eu-west-3 as a possible default datasource

public/app/plugins/datasource/cloudwatch/partials/config.html

@@ -39,7 +39,7 @@
   <div class="gf-form">
     <label class="gf-form-label width-13">Default Region</label>
     <div class="gf-form-select-wrapper max-width-18 gf-form-select-wrapper--has-help-icon">
-      <select class="gf-form-input" ng-model="ctrl.current.jsonData.defaultRegion" ng-options="region for region in ['ap-northeast-1', 'ap-northeast-2', 'ap-southeast-1', 'ap-southeast-2', 'ap-south-1', 'ca-central-1', 'cn-north-1', 'cn-northwest-1', 'eu-central-1', 'eu-west-1', 'eu-west-2', 'sa-east-1', 'us-east-1', 'us-east-2', 'us-gov-west-1', 'us-west-1', 'us-west-2']"></select>
+      <select class="gf-form-input" ng-model="ctrl.current.jsonData.defaultRegion" ng-options="region for region in ['ap-northeast-1', 'ap-northeast-2', 'ap-southeast-1', 'ap-southeast-2', 'ap-south-1', 'ca-central-1', 'cn-north-1', 'cn-northwest-1', 'eu-central-1', 'eu-west-1', 'eu-west-2', 'eu-west-3', 'sa-east-1', 'us-east-1', 'us-east-2', 'us-gov-west-1', 'us-west-1', 'us-west-2']"></select>
       <info-popover mode="right-absolute">
         Specify the region, such as for US West (Oregon) use ` us-west-2 ` as the region.
       </info-popover>