Update connect server URL in test proxy configuration

[martynmjones]

Changes proposed in this Pull Request:

Closes #2446

Updates the test proxy configuration to set the connect server URL to https://api.woocommerce.com as this was missed when the service was originally migrated.

Detailed test instructions:

1. Run npm run test-proxy
2. Confirm the correct connect server URL is displayed in the output
   • Proxy server running on http://localhost:5555 > https://api.woocommerce.com in default mode
3. Confirm the test data is displayed when viewing reports in Marketing > Google Listings & Ads

Changelog entry

Dev - Update connect server URL in test proxy configuration

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 63.4%. Comparing base (4d50b73) to head (3112bd3).
Report is 8 commits behind head on develop.

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #2447   +/-   ##
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  Coverage     63.4%   63.4%           
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  Files          321     321           
  Lines         5027    5027           
  Branches      1219    1219           
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  Hits          3188    3188           
  Misses        1672    1672           
  Partials       167     167           

Flag	Coverage Δ
js-unit-tests	63.4% <ø> (ø)

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[ianlin]

Thanks for the update, tested locally and it worked as expected as described. 👍