Describe the problem

See the detailed analysis here.

We need to make structural improvements to the span lifecycle (document, simplify, introduce invariant checks, testing, etc) that avoid this class of bugs.

See also #86547 and all the other work in CRDB-25287 (which is related and made important simplifications, but didn't focus on the span lifecycles in particular).

To Reproduce

Unclear

Jira issue: CRDB-30092