[chore] service/telemetry: remove unused type alias

[axw]

Description

Since open-telemetry/opentelemetry-collector-contrib#41963 was merged, there are no more references to this type alias.

Link to tracking issue

Related to #4970

Testing

N/A

Documentation

N/A

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 91.68%. Comparing base (cd46300) to head (6d023a0).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #13891      +/-   ##
==========================================
- Coverage   91.69%   91.68%   -0.01%     
==========================================
  Files         652      652              
  Lines       42506    42506              
==========================================
- Hits        38976    38972       -4     
- Misses       2725     2728       +3     
- Partials      805      806       +1     

☔ 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.

[dmathieu]

Technically, this is a breaking change so I think a changelog entry would be nice.

[axw]

@dmathieu fair enough, added

[codeboten]

Please follow the procedure to deprecate the type first and it can be removed in the following version https://github.com/open-telemetry/opentelemetry-collector/blob/main/docs/coding-guidelines.md#api-breaking-changes

[axw]

👍 I had previously added a disclaimer comment, but didn't explicitly create a deprecation notice. Will open a new PR and revive this later.

[axw]

#13904