internal/trace: reorganize into multiple files
Created by: bobheadxi
We hope to address tracing soon, with the deprecation of Datadog (https://github.com/sourcegraph/sourcegraph/issues/37568) and upcoming migration to OTel tracing (https://github.com/sourcegraph/sourcegraph/issues/27386). In prep, I did a review of the trace
package and am hoping to split up the massive traceutil.go
into more understandable chunks
Test plan
CI passes still, there's no logic changes here so we should be good