jaeger: limit operation cardinality by using route regex
While jaeger can handle high-cardinality fields quite well, it's still recommended to limit the cardinality of operation (aka "span name").
This has implications for the operation dropdown:
It also has implications for the dependency graph, which is currently running out of memory when trying to process the spans, see https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/11652.
Prior to this change, workhorse traces included the full URL in the operation name:
With this change applied, we now only have the route regex:
It's worth noting that we're missing individual method and path tags on the root span itself, I am going to address that upstream in labkit.
See also:
cc @andrewn @mwasilewski-gitlab
refs https://gitlab.com/gitlab-com/gl-infra/infrastructure/-/issues/11676