test: use previously created experiment for pause test

[emily-roses]

Ticket

Description

Instead of creating a new experiment mid-test (which may have been interrupting other tests), use previously created experiment.

Test Plan

Checklist

• Changes have been manually QA'd
• New features have been approved by the corresponding PM
• User-facing API changes have the "User-facing API Change" label
• Release notes have been added as a separate file under docs/release-notes/
  See Release Note for details.
• Licenses have been included for new code which was copied and/or modified from any external code

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[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 49.79%. Comparing base (287faf7) to head (004f86d).
Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #9727      +/-   ##
==========================================
- Coverage   54.11%   49.79%   -4.33%     
==========================================
  Files        1257      934     -323     
  Lines      154854   125521   -29333     
  Branches     3485     3486       +1     
==========================================
- Hits        83801    62499   -21302     
+ Misses      70907    62876    -8031     
  Partials      146      146              

Flag	Coverage Δ
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