trace: remove deprecated OpenTracing backends

[timvaillancourt]

Description

This completes the v25 OpenTracing cleanup announced in #19619. The opentracing-jaeger and opentracing-datadog backends were deprecated in v24 with a migration path to --tracer opentelemetry — this removes them so we're running a single tracing implementation

Deleted opentracing.go, plugin_jaeger.go, plugin_datadog.go, logger.go (and their tests) from go/trace/. Also migrated vtadmin/grpcserver which was the only place still using opentracing.GlobalTracer() directly — it now uses trace.AddGrpcServerOptions() like everything else

Dependencies dropped: opentracing-go, opentracing-contrib/go-grpc, uber/jaeger-client-go, uber/jaeger-lib, dd-trace-go.v1 and their transitive deps

Breaking: --tracer opentracing-jaeger and --tracer opentracing-datadog no longer work. The following flags are also removed: --jaeger-agent-host, --tracing-sampling-type, --datadog-agent-host, --datadog-agent-port, --datadog-trace-debug-mode. The JAEGER_SAMPLER_PARAM env var no longer sets --tracing-sampling-rate

Checkout that go.mod cleanup (8 x direct/39 indirect dependencies 🧹) 😮!

Related Issue(s)

1. Resolves: Feature Request: Remove deprecated OpenTracing tracing backends in v25 #19940
2. Follow-up to trace: add OpenTelemetry backend, deprecate OpenTracing #19619
3. Website docs for v25 Copy latest tracing.md docs to v25 website#2099

Checklist

• "Backport to:" labels have been added if this change should be back-ported to release branches
• If this change is to be back-ported to previous releases, a justification is included in the PR description
• Tests were added or are not required
• Did the new or modified tests pass consistently locally and on CI?
• Documentation was added or is not required

Deployment Notes

Users running --tracer opentracing-jaeger or --tracer opentracing-datadog must switch to --tracer opentelemetry before upgrading to v25. The deprecation warning added in v24 (#19619) pointed to the migration path

AI Disclosure

This PR was written primarily by Claude Code — I provided direction on the cleanup scope. Claude also prepared this PR summary

[vitess-bot]

Review Checklist

Hello reviewers! 👋 Please follow this checklist when reviewing this Pull Request.

General

• Ensure that the Pull Request has a descriptive title.
• Ensure there is a link to an issue (except for internal cleanup and flaky test fixes), new features should have an RFC that documents use cases and test cases.

Tests

• Bug fixes should have at least one unit or end-to-end test, enhancement and new features should have a sufficient number of tests.

Documentation

• Apply the release notes (needs details) label if users need to know about this change.
• New features should be documented.
• There should be some code comments as to why things are implemented the way they are.
• There should be a comment at the top of each new or modified test to explain what the test does.

New flags

• Is this flag really necessary?
• Flag names must be clear and intuitive, use dashes (-), and have a clear help text.

If a workflow is added or modified:

• Each item in Jobs should be named in order to mark it as required.
• If the workflow needs to be marked as required, the maintainer team must be notified.

Backward compatibility

• Protobuf changes should be wire-compatible.
• Changes to _vt tables and RPCs need to be backward compatible.
• RPC changes should be compatible with vitess-operator
• If a flag is removed, then it should also be removed from vitess-operator and arewefastyet, if used there.
• vtctl command output order should be stable and awk-able.

[codecov]

Codecov Report

❌ Patch coverage is 20.00000% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 48.91%. Comparing base (70c7a72) to head (fb4b14b).
⚠️ Report is 194 commits behind head on main.

Files with missing lines	Patch %	Lines
go/vt/vtadmin/grpcserver/server.go	25.00%	3 Missing ⚠️
go/trace/trace.go	0.00%	1 Missing ⚠️

❗ There is a different number of reports uploaded between BASE (70c7a72) and HEAD (fb4b14b). Click for more details.

HEAD has 1 upload less than BASE

Flag	BASE (70c7a72)	HEAD (fb4b14b)
	1	0

Additional details and impacted files

@@             Coverage Diff             @@
##             main   #19939       +/-   ##
===========================================
- Coverage   69.67%   48.91%   -20.76%     
===========================================
  Files        1614        6     -1608     
  Lines      216793      462   -216331     
===========================================
- Hits       151044      226   -150818     
+ Misses      65749      236    -65513     

Flag	Coverage Δ
partial	48.91% <20.00%> (?)

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[Copilot]

Pull request overview

Copilot reviewed 21 out of 22 changed files in this pull request and generated 1 comment.

[promptless]

Promptless prepared a documentation update related to this change.

Triggered by vitessio/vitess#19939

Updated VTAdmin reference docs to replace deprecated --tracer "opentracing-jaeger" examples with --tracer opentelemetry, and removed the now-deleted --tracing-sampling-type flag from the vtadmin reference. This complements website PR #2099 which updated the main tracing guide.

Review: Remove stale OpenTracing references from v25 VTAdmin docs

[timvaillancourt]

Website PR: vitessio/website#2100

[mattlord]

Thanks, @timvaillancourt ! ❤️