fix: change from drop rows to upsert rows, remove unused vars (#2630)

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_drop: true
 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"

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

@@ -9,15 +9,8 @@
   with_items:
   - "{{ graylog_mongo_collections.split(',') }}"
 
-- name: drop and restore the data to mongodb
-  shell: "mongoimport --drop --db={{ graylog_mongo_db }} --collection={{ item }} --file={{ mongo_json_data }}/{{ item }}.json"
-  when: graylog_mongo_collections_drop
-  with_items:
-  - "{{ graylog_mongo_collections.split(',') }}"
-
-- name: restore the data to mongodb
-  shell: "mongoimport --db={{ graylog_mongo_db }} --collection={{ item }} --file={{ mongo_json_data }}/{{ item }}.json"
-  when: not graylog_mongo_collections_drop
+- name: insert/upsert the data to mongodb
+  shell: "mongoimport --mode upsert --db={{ graylog_mongo_db }} --collection={{ item }} --file={{ mongo_json_data }}/{{ item }}.json"
   with_items:
   - "{{ graylog_mongo_collections.split(',') }}"