.gitlab/scripts: remove BenchmarkConcurrentTracing from CI benchmarks (…

…#1845)

We replace BenchmarkConcurrentTracing with BenchmarkTracerAddSpans, which
should provide more reliable benchmarks about the cost of starting spans.

BenchmarkConcurrentTracing is not a reliable test and seems to mostly end
up testing the contention characteristics of the system it's running on.

.gitlab-ci.yml

@@ -8,7 +8,7 @@ variables:
   INDEX_FILE: index.txt
   KUBERNETES_SERVICE_ACCOUNT_OVERWRITE: dd-trace-go
   FF_USE_LEGACY_KUBERNETES_EXECUTION_STRATEGY: "true"
-  BENCHMARK_TARGETS: "BenchmarkConcurrentTracing|BenchmarkStartSpan|BenchmarkSingleSpanRetention|BenchmarkOTelApiWithCustomTags|BenchmarkInjectW3C|BenchmarkExtractW3C"
+  BENCHMARK_TARGETS: "BenchmarkTracerAddSpans|BenchmarkStartSpan|BenchmarkSingleSpanRetention|BenchmarkOTelApiWithCustomTags|BenchmarkInjectW3C|BenchmarkExtractW3C"
 
 include:
   - ".gitlab/benchmarks.yml"

CONTRIBUTING.md

@@ -68,4 +68,3 @@ Some benchmarks will run on any new PR commits, the results will be commented in
 #### Adding a new benchmark
 To add additional benchmarks that should run for every PR, go to `.gitlab-ci.yml`.
 Add the name of your benchmark to the `BENCHMARK_TARGETS` variable using pipe character separators. 
-