Publish runtime metric in seconds

[VladLazar]

Note: Depends on https://github.com/redpanda-data/seastar/pull/31.

Cover letter

This PR adds the following new metric: Name: redpanda_scheduler_runtime_seconds Description: Accumulated runtime of task queue associated with this scheduling group Labels:

• redpanda_scheduling_group
• shard

Backport Required

• [X] not a bug fix
• [ ] papercut/not impactful enough to backport
• [ ] v22.2.x
• [ ] v22.1.x
• [ ] v21.11.x

UX changes

• none

Release notes

• none

[BenPope]

I don't think the sum of these is the same as vectorized_reactor_cpu_busy_ms. So maybe we should add redpanda_cpu_busy_seconds_total?

[VladLazar]

No, it's not. I think the "busy time" includes the wait time too. Sure, we can add it. It's already exposed by the reactor.

[VladLazar]

Changes in force push:

• publish scheduler stats from the default group too
• added redpanda_application_uptime_seconds_total and redpanda_application_busy_seconds_total

[BenPope]

I set this for backport to v22.2.x

[VladLazar]

Awesome.

I built and tested this locally

Appreciate that. Thanks for trying!

[BenPope]

/backport v22.2.x