chore: move sdk-trace-web utils to web-common

[david-luna]

Which problem is this PR solving?

SDK 3.0 will have a single sdk-trace package. Even in the last JS SIG (2026-09-02) it was mentioned a plan to remove the sdk-trace-* packages.

fetch and XmlHttpRequest share code through @opentelemetry/sdk-trace-web package. The code is a set of utility functions to operate with resource timing entries and Span events. Keeping that dependency means devs will install the deprecated packages even if the migrate to the new major version.

By moving the utils to @opentelemetry/web-common we make the fetch and XmlHttpRequest ready for the new SDK version without breaking compatibility.

Type of change

Please delete options that are not relevant.

• Refactor (non-breaking change which fixes an issue)

How Has This Been Tested?

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

• Unit tests in the instrumentation packages
• New Unit tests in web-common package

Checklist:

• Followed the style guidelines of this project
• Unit tests have been added

[opentelemetry-pr-dashboard]

Pull request dashboard status

Waiting on maintainers · refreshed 2026-09-08 08:43 UTC

Merge when ready.

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[codecov]

Codecov Report

❌ Patch coverage is 70.79208% with 59 lines in your changes missing coverage. Please review.
✅ Project coverage is 94.66%. Comparing base (241d86b) to head (4c17ec7).

Files with missing lines	Patch %	Lines
.../packages/web-common/src/utils-resource-timings.ts	66.28%	59 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #7058      +/-   ##
==========================================
- Coverage   95.00%   94.66%   -0.34%     
==========================================
  Files         407      409       +2     
  Lines       14342    14543     +201     
  Branches     3289     3345      +56     
==========================================
+ Hits        13625    13767     +142     
- Misses        717      776      +59     

Files with missing lines	Coverage Δ
...s/opentelemetry-instrumentation-fetch/src/fetch.ts	83.17% <100.00%> (ø)
...s/opentelemetry-instrumentation-fetch/src/utils.ts	89.01% <ø> (ø)
...etry-instrumentation-xml-http-request/src/utils.ts	84.48% <ø> (ø)
...emetry-instrumentation-xml-http-request/src/xhr.ts	93.22% <ø> (ø)
...ges/web-common/src/enums/PerformanceTimingNames.ts	100.00% <100.00%> (ø)
experimental/packages/web-common/src/semconv.ts	100.00% <100.00%> (ø)
.../packages/web-common/src/utils-resource-timings.ts	66.28% <66.28%> (ø)

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[pichlermarc]

the simple move from @opentelemetry/sdk-trace-web to @opentelemetry/web-common looks good.

I'm leaving out any comments about the actual code being moved (the utilities have some confusing signatures for historical reasons) - we can improve that in follow-ups if needed.