feat: support lab_mergeFeedEnabled (#1335)

[myConsciousness]

Checklist

• The title of my PR starts with a Conventional Commit prefix (fix:, feat:, docs: etc).
• I have read the Contributor Guide and followed the process outlined for submitting PRs.
• I have updated/added tests for new/updated/fixed functionality.
• I have updated/added dartdoc comments with ///.

Breaking Change

• Yes, this is a breaking change.
• No, this is not a breaking change.

Related Issues

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✅ Deploy Preview for jade-haupia-45bdc2 canceled.

Name	Link
🔨 Latest commit	05c89f6
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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 78.84%. Comparing base (2708804) to head (05c89f6).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1336      +/-   ##
==========================================
- Coverage   79.64%   78.84%   -0.80%     
==========================================
  Files         370      349      -21     
  Lines        4401     4103     -298     
==========================================
- Hits         3505     3235     -270     
+ Misses        896      868      -28     

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