Gather max_time and stddev_time from pg_stat_statements through gitlab-exporter

As per discussions regarding monitoring of queries performance regression after setting changes, eg. production#7840 (comment 1142457574), we need to gather also the max_time (max_exec_time for PG13) and stddev_time through the gitlab-exporter https://gitlab.com/gitlab-cookbooks/gitlab-exporters/-/blob/master/templates/postgres_exporter/queries.yaml.erb#L282

Tasks:

• MR to update queries.yaml in the gitlab-exporter
• MR to bump gitlab-exporter through Chef into GSTG
• Validate/test in GSTG
• MR to bump gitlab-exporter through Chef into GPRD