E2E - Migrate dev tools flows to use WP-CLI

[achyuthajoy]

Fixes #4402

Changes proposed in this Pull Request

Previously, enabling features via dev tools was done like a regular test flow, which is not ideal since dev tools features are used only for development. This PR adds updates the dev tools flows to use WP-CLI

Testing instructions

• Confirm the E2E tests on this PR is passing as expected.
• Confirm that the test shopper-myaccount-save-card-and-checkout-upe.spec.js under WCPay - Shopper is passing since the test uses the new WPCLI flows.
• Performance tests can be tested locally by running npm run test:e2e-performance

---

• Run npm run changelog to add a changelog file, choose patch to leave it empty if the change is not significant. You can add multiple changelog files in one PR by running this command a few times.
• Covered with tests (or have a good reason not to test in description ☝️)
• Tested on mobile (or does not apply)

Post merge

• Link to testing instructions from release testing doc following these instructions : Add link here / 'QA Testing Not Applicable'
• Add or update critical flows and testing instructions for critical flows, if applicable.
• Add what's changed (description, screenshot, demo videos etc.) to the release announcement post, if applicable.

[jbordonado]

This should save some precious time for setting up the context of tests.
I'm pre-approving, let's double check that the E2E tests are indeed passing once the run is done

[achyuthajoy]

@jbordonado We'll need to put this PR on-hold for now. It seems the command is not getting executed inside GH actions. Need to investigate.

Can confirm that it's working as expected locally.