Add Redis timing buckets of 1s and 2s

What does this MR do?

Most transactions use far less than a second in Redis, but we see some Sidekiq jobs with p95 timings over half a second, and p99 timings of over a second. (These values are from structured logging, which records exact timings.)

Adding these buckets gives us a better picture in Prometheus, too.

I got these values from https://log.gprd.gitlab.net/goto/efc94043d4992ef617e77b6c43f9f592.

json.queue.keyword: Descending	50th percentile of json.redis_duration_s	90th percentile of json.redis_duration_s	95th percentile of json.redis_duration_s	99th percentile of json.redis_duration_s
authorized_project_update:authorized_project_update_user_refresh_with_low_urgency	0.069	0.43	0.61	1.184
repository_update_mirror	0.012	0.168	0.325	0.974
authorized_projects	0.093	0.368	0.515	0.929
update_project_statistics	0.008	0.118	0.278	0.821
detect_repository_languages	0.007	0.101	0.233	0.706
post_receive	0.017	0.089	0.159	0.537
jira_importer:jira_import_import_issue	0.003	0.045	0.122	0.536

Although when I checked last week more than one queue was exceeding 1s in the p99 case: gitlab-com/gl-infra/scalability#411 (comment 359678881)

For gitlab-com/gl-infra/scalability#411 (closed).