Glutton Benchmarking Enhancements

[Max Smythe (maxsmythe)]

Benchmarking: multi-actor glutton VUs, live window, resume retries, client-side latency

Glutton actors per VU. Each VU creates --actors-per-user actors on
startup and cycles through them round-robin, so one goroutine can drive
many mostly-idle actors. runner.py forwards the flag to boomer-glutton.
A crashed actor stays crashed for the run (ateapi never rehabilitates
it), so it is marked on the first Aborted "crashed" error, skipped from
then on, and counted in a CrashCount stat.

Live window. --min/--max-live-time (default 0-0) set how long an actor
stays resumed between its first ping and the suspend. Up to
--max-pings-per-wake pings (default 1) run inside it, spaced 0.2-1.0s
apart. The wait window (--min/--max-wait-time) remains the gap between
one actor's suspend and the VU's next resume, and every return path
sleeps it, so a failing startUser, resume, or crashed actor does not
spin on boomer's zero-delay re-entry. With the defaults the cycle is
resume, ping, suspend, wait: the same shape as before.

Resume retries. ResumeActor retries ateapi's transient "concurrent
update conflict" Aborted up to five times with a 50ms backoff, inside
the timed call, so the conflict no longer shows up as a failure.

Client-side latency. Every gRPC row in the locust stats now reports
client wall clock, which covers retries, queueing, and the network. The
server's elapsed-time trailer stays on the trace span only.

Worker robustness. The router HTTP client keeps up to 10000 idle
connections per host so each VU reuses its connection across wakes. A
failed dynconfig fetch after the first successful one keeps the last
fetched values instead of exiting the worker.

Orchestrator. util.run logs the duration of each shell command.

Fixes #<issue_number_goes_here>

It's a good idea to open an issue first for discussion.

• Tests pass
• Appropriate changes to documentation are included in the PR