ref(code-review): Log GH -> seer request time

[kddubey]

seems like there isn't a way to get this data today, so including it in this existing log. ideally this is a metric, but i'm not sure about cardinality. lmk if i can safely add

[armenzg]

For context, trigger_at comes from here:

sentry/src/sentry/seer/code_review/utils.py

Lines 130 to 134 in 42a0e93

	trigger_at = (
	pull_request.get("updated_at")
	or pull_request.get("created_at")
	or datetime.now(timezone.utc).isoformat()
	)

The recording of the metric happens at the end of the task execution:

sentry/src/sentry/seer/code_review/webhooks/task.py

Lines 147 to 148 in 7302e23

	if should_record_latency:
	record_latency(status, enqueued_at_str)

The only metric we have on the Sentry side can be seen here (region -> Seer call happens):
https://app.datadoghq.com/dashboard/6x2-jgc-kiz/code-review?fromUser=false&fullscreen_end_ts=1770650225142&fullscreen_paused=false&fullscreen_refresh_mode=sliding&fullscreen_section=overview&fullscreen_start_ts=1770045425142&fullscreen_widget=2461630282246654&refresh_mode=sliding&from_ts=1770645956120&to_ts=1770649556120&live=true

@vaind is already adding latency metrics here: https://github.com/getsentry/seer/pull/4710

If we wanted further granularity we could add these metrics:

• GitHub -> control
• control -> region

Once we see @vaind 's metrics live we can determine if we need further granularity.