Add Latency Quantiles (like 99% Query Time) to Statements

[breezewish]

Feature Request

Is your feature request related to a problem? Please describe:

Now only avg, max and min latency are displayed, which is usually not enough for real-world scenarios. For example, in grafana, we usually look at 90%, 99% or even 99.9% metrics. This capability is now missing when looking at statements.

Describe the feature you'd like:

Add quantiles to important statement fields:

• LATENCY
• COP_PROCESS_TIME
• COP_WAIT_TIME
• TOTAL_KEYS
• PROCESSED_KEYS
• WRITE_KEYS
• PREWRITE_TIME
• COMMIT_TIME

Describe alternatives you've considered:

Teachability, Documentation, Adoption, Migration Strategy:

This feature can be implemented by adding buckets (like Prometheus) to the different latency fields and then use algorithms same to Prometheus to aggregate these buckets to get a specific quantile latency as demand.

[wwar]

See also: #15349