[Stack Monitoring] Update metricbeat's elasticsearch mappings

[crespocarlos]

Following up the work done in elastic/kibana#141305, we need also need to update metricbeat's mapping

[matschaffer]

From examining https://github.com/elastic/elasticsearch/pull/90203/files it looks like the changes are:

• pending_tasks.(time_in_queue,source,priority,insert_order,ms) - remove extra nexting, move fields under pending_tasks, remove pending_task
• add indices.bulk object with operations, total_size, avg_size,total_time,avg_time
• add shards.primaries (long)
• add total.bulk object with avg_time_in_millis,avg_size_in_bytes,total_time_in_millis,total_operations,total_size_in_bytes