WOOMOB-1340

Description

• Integrates new garden related fields introduced for Sites endpoint in the PR.
• Updates CIABEligibilityChecker by removing the temp mock logic with the relevant logic based on new "Garden" fields in Site model.
• The new logic now checks if the is_garden field is true and the garden_name equals to "commerce" to determine the CIAB environment.
• Adds tests for CIABEligibilityChecker basing on the new logic.

Note: the majority of changes in the diff are introduced by the new 126th data model version.

Non-CIAB site smoke test

• Login into our shared testing site or your personal site that wasn't created by the Garden API demo tool.
• The easiest way to verify the existing CIAB/non-CIAB behaviour is check if "Payments" and "Blaze" options are presented in "Menu".
• So navigate to Menu in bottom tab.
• Make sure Payments and Blaze options are presented.

CIAB site testing steps

• Use the Garden API demo tool. and create a testing Garden based site.
• Login into the site with your wp.com account using the "W" logo in web tool
• Login into the site on mobile app
• Repeat the checking step from the Non-CIAB site smoke test, i.e. navigate to the Menu and make sure "Blaze" and "Payments" are hidden.

• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.