Reduce the number of buckets for ElasticSearch

What does this MR do?

These are buckets of the time spent in ElasticSearch within a transaction.

I based the buckets on the times I found the past 24h in the logs: https://log.gprd.gitlab.net/goto/48a7d0aaddeba6f80c4aa2845ca6e5d0

These metrics are currently not being used in alerts or dashboards, but they're supposed to be at some point. So for now, just reducing the cardinality on them.

Part of gitlab-com/gl-infra/scalability#460

Does this MR meet the acceptance criteria?

Conformity

• [-] Changelog entry
• [-] Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content