Tracing for tests (with OTEL Agent)

[dsmiley]

Some documentation and small amount of gradle to help people using OTEL tracing when working on a test.

First iteration includes a commit of stuff that enhances spans with more detail. Such stuff belongs in another issue/PR.

[dsmiley]

I spent the better part of the day playing with Jaeger, reading OTEL info, and generally re-creating something similar that I had at my last job, including improving spans detail. CoPilot Agent helped.
For the technique to be any good, there ought to be at least the same info in the request logs. That was lacking, so I enhanced it and then some. If someone were to expand on this technique further, I'd like to see a Log4j2 appender that puts log messages (thus not just request logs) on the spans. Yes, spans can have logs and ours have some already.

Jaeger 2 is pretty great! A major improvement over v1.