make BULK_BATCH_SIZE value configurable through settings API

Author: NickOvt

lib/settings-handler.js

@@ -138,6 +138,15 @@ const SETTING_KEYS = [
             .allow('')
             .trim()
             .pattern(/^\d+\s*[a-z]*(\s*,\s*\d+\s*[a-z]*)*$/)
+    },
+
+    {
+        key: 'const:max:bulk_batch_size',
+        name: 'Max bulk batch write size',
+        description: 'The maximum number of entries that are collected and then written with mongodb insertMany in one insert query.',
+        type: 'number',
+        constKey: 'BULK_BATCH_SIZE',
+        schema: Joi.number()
     }
 ];