cli: include active trace spans in debug.zip

[tbg]

Is your feature request related to a problem? Please describe.
Now that we have a way to observe long-running trace spans, we should also include them in debug.zip:

#55592

Describe the solution you'd like
Either dump (a suitably filtered) select on #55733 or add and hit an API endpoint straight into the registry.

The latter might be preferrable if we want Jaeger-compatible output.

Describe alternatives you've considered

Additional context

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[tbg]

Note that this motivates #58610

[angelapwen]

Just noticed this issue: have already included a select into debug.zip for the long-running trace spans vtable in #59492 but we can leave this open if we want the Jaeger-compatible output.

[tbg]

To close this issue, we should also include the payloads for all of the long-running trace spans via #60922.