fix: removed whitespaces to resolve template copy

ansible/roles/graylog-mongodb-import/defaults/main.yml

 graylog_mongo_db: "graylog"
 mongo_master: "{{ groups['graylog'][0] }}"
 mongo_json_data: /tmp/mongo_json_data
-graylog_mongo_collections: "cluster_config, content_packs, content_packs_installations, event_definitions, event_notifications, event_notification_status, grants, grok_patterns, index_sets, inputs, lut_caches, lut_data_adapters, lut_tables, pipeline_processor_pipelines, pipeline_processor_pipelines_streams, pipeline_processor_rules, roles, scheduler_job_definitions, scheduler_triggers, searches, streamrules, streams, users, views"
+graylog_mongo_collections: "cluster_config,content_packs,content_packs_installations,event_definitions,event_notifications,event_notification_status,grants,grok_patterns,index_sets,inputs,lut_caches,lut_data_adapters,lut_tables,pipeline_processor_pipelines,pipeline_processor_pipelines_streams,pipeline_processor_rules,roles,scheduler_job_definitions,scheduler_triggers,searches,streamrules,streams,users,views"