Support for the timeouts, and tests for them, was added in
53a8b2ac87 -- though no code could have set them after 31597cf33e.
Add a 10-second default timeout. Observationally, p99 is just about
5s, with everything else being previously being destined to meet the
30s worker timeout; 10s provides a sizable buffer between them.
Fixes#17742.