Extend vulture to generate long-running traces

[kvrhdn]

Is your feature request related to a problem? Please describe.
Vulture currently generates random traces and sends them in a single batch to Tempo. To improve our test coverage we'd also like to send long-running traces, i.e. traces that will span multiple blocks in Tempo.

The ingester considers a trace complete after a configurable idle period (by default 30s). If vulture can send spans with a longer delay between them they should end up in different blocks and Tempo will have to do additional work to combine all spans into a single trace when requested.

Describe the solution you'd like
Vulture is currently stateless and ideally it stays stateless.

The following should probably be configurable:

• a setting to enable/disable long-running traces
• the delay between send requests

Describe alternatives you've considered

Additional context