Set WPCOM_API_STATUS transient for E2E tests

[martynmjones]

Changes proposed in this Pull Request:

Closes #2587

Updates E2E test data to set the default value for WPCOM_API_STATUS.

Detailed test instructions:

1. Checkout fix/2587-e2e-tests
2. npm run test:e2e

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 65.3%. Comparing base (bf5c219) to head (1c6a902).
Report is 2 commits behind head on develop.

Additional details and impacted files

@@            Coverage Diff            @@
##             develop   #2588   +/-   ##
=========================================
  Coverage       65.3%   65.3%           
  Complexity      4596    4596           
=========================================
  Files            474     474           
  Lines          17893   17893           
=========================================
  Hits           11685   11685           
  Misses          6208    6208           

Flag	Coverage Δ
php-unit-tests	65.3% <ø> (ø)

Flags with carried forward coverage won't be shown. Click here to find out more.

[martynmjones]

Merged without review as it's a small dev facing change