Metric to report time spent fetching and analyzing segments

[suneet-s]

Description

Add a new metric that is emitted by the compaction task that shows how much time it spent fetching and analyzing segments. When a datasource is very fragmented, this could be a large amount of time. This metric will be helpful to operators as they can monitor this to see if they would benefit from explicitly specifying the schema in the auto compaction / manual compaction config if their use case allows it.

Here is a sample of what the metric would look like

{"taskIngestionMode":"REPLACE_LEGACY","feed":"metrics","taskType":"compact","metric":"compact/segmentAnalyzer/fetchAndProcessMillis","service":"druid/middleManager","groupId":"coordinator-issued_compact_wikipedia_cgmonfmg_2023-08-04T00:35:38.106Z","host":"localhost:8100","version":"28.0.0-SNAPSHOT","value":78,"dataSource":"wikipedia","taskId":"coordinator-issued_compact_wikipedia_cgmonfmg_2023-08-04T00:35:38.106Z","timestamp":"2023-08-04T00:35:40.605Z"}

Release note

NEW: compact/segmentAnalyzer/fetchAndProcessMillis is now reported by compaction tasks to indicate how much time was spent fetching and processing segments to infer the schema

This PR has:

• been self-reviewed.
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.

[zachjsh]

Is this used?

[suneet-s]

removed. I had thought perhaps a metric for all the time spent in this class would be interesting, but decided against implementing it as it would have resulted in a few new metrics.

[ektravel]

Reviewed metrics.md and left some suggestions.

[suneet-s]

Thanks @ektravel and @zachjsh for the reviews