chore: update 2.9.4 CHANGELOG to match GitHub release note

[erikayasuda]

We made a small change to the release note for 2.9.4. Matching the CHANGELOG to reflect this.

Checklist

• PR author has checked that all the criteria below are met
• The PR description includes an overview of the change
• The PR description articulates the motivation for the change
• The change includes tests OR the PR description describes a testing strategy
• The PR description notes risks associated with the change, if any
• Newly-added code is easy to change
• The change follows the library release note guidelines
• The change includes or references documentation updates if necessary
• Backport labels are set (if applicable)

Reviewer Checklist

• Reviewer has checked that all the criteria below are met
• Title is accurate
• All changes are related to the pull request's stated goal
• Avoids breaking API changes
• Testing strategy adequately addresses listed risks
• Newly-added code is easy to change
• Release note makes sense to a user of the library
• If necessary, author has acknowledged and discussed the performance implications of this PR as reported in the benchmarks PR comment
• Backport labels are set in a manner that is consistent with the release branch maintenance policy

[github-actions]

CODEOWNERS have been resolved as:

CHANGELOG.md                                                            @DataDog/apm-python

[datadog-dd-trace-py-rkomorn]

Datadog Report

Branch report: erikayasuda/2.9.4-releasenote-fix
Commit report: b40b3d4
Test service: dd-trace-py

✅ 0 Failed, 146404 Passed, 31874 Skipped, 7h 6m 15.97s Total duration (1m 2.39s time saved)