Skip system collections in getBucketInfos

Issue: ARSN-447

lib/storage/metadata/mongoclient/MongoClientInterface.js

@@ -2106,6 +2106,14 @@ class MongoClientInterface {
             name.startsWith('__');
     }
 
+    /*
+     * return true if it a system collection, reserved by Mongo for internal use: and which should
+     * not be used.
+     */
+    _isSystemCollection(name) {
+        return name.startsWith('system.');
+    }
+
     /*
      * get bucket related information for count items, used by cloudserver
      * and s3utils
@@ -2116,7 +2124,7 @@ class MongoClientInterface {
 
         this.db.listCollections({ type: 'collection' }).toArray().then(collInfos =>
             async.eachLimit(collInfos, 10, (value, next) => {
-                if (this._isSpecialCollection(value.name)) {
+                if (this._isSystemCollection(value.name) || this._isSpecialCollection(value.name)) {
                     // skip
                     return next();
                 }