Replace the HTTP-mode outbound test that spun up a SOCKS inbound and
ran an httptrace'd request from the Go client with a probe-only xray
config: burstObservatory probes the target outbound directly and the
result is read from xray's /debug/vars metrics endpoint.
The probe lives inside xray, so the measured delay and failure
reasons reflect what xray itself sees over the real proxy chain.
Drops the DNS/Connect/TLS/TTFB breakdown (and statusCode) since the
observatory snapshot only exposes total delay; the frontend popover
is updated accordingly.
31d7ed5103