Replaces OAuth2 section with self-hosted test instructions

[antonis]

Description

This PR temporarily removes the OAuth2 section of the readme and adds instructions for testing with a self-hosted site. The reason for this change is that the introduction of Passkey support and the related WordPress.com API changes have broken the WordPress.com OAuth2 Authentication flow in the apps.

Internal ref: pbArwn-6qJ-p2

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To Test:

Check the README

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Regression Notes

1. Potential unintended areas of impact

   • N/A

2. What I did to test those areas of impact (or what existing automated tests I relied on)

   • N/A

3. What automated tests I added (or what prevented me from doing so)

   • N/A

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PR Submission Checklist:

• I have completed the Regression Notes.
• I have considered adding accessibility improvements for my changes.
• I have considered if this change warrants user-facing release notes and have added them to RELEASE-NOTES.txt if necessary.

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Testing Checklist (strike-out the not-applying and unnecessary ones):

• WordPress.com sites and self-hosted Jetpack sites.
• Portrait and landscape orientations.
• Light and dark modes.
• Fonts: Larger, smaller and bold text.
• High contrast.
• Talkback.
• Languages with large words or with letters/accents not frequently used in English.
• Right-to-left languages. (Even if translation isn’t complete, formatting should still respect the right-to-left layout)
• Large and small screen sizes. (Tablet and smaller phones)
• Multi-tasking: Split screen and Pop-up view. (Android 10 or higher)

[wpmobilebot]

📲 You can test the changes from this Pull Request in Jetpack by scanning the QR code below to install the corresponding build.

	App Name	Jetpack
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr20928-01ab55f
	Commit	01ab55f
	Direct Download	jetpack-prototype-build-pr20928-01ab55f.apk

Note: Google Login is not supported on these builds.

[wpmobilebot]

📲 You can test the changes from this Pull Request in WordPress by scanning the QR code below to install the corresponding build.

	App Name	WordPress
	Flavor	Jalapeno
	Build Type	Debug
	Version	pr20928-01ab55f
	Commit	01ab55f
	Direct Download	wordpress-prototype-build-pr20928-01ab55f.apk

Note: Google Login is not supported on these builds.

[irfano]

I was wondering if we should mention that the WP login will be temporarily unavailable. But, most features are already available with self-hosted sites, so it seems fine not to mention it. You can merge after considering my np comment. Thank you for taking care of this.

[sonarcloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
No data about Coverage
No data about Duplication

See analysis details on SonarCloud

[antonis]

Thank you for the prompt review @irfano 🙇

I was wondering if we should mention that the WP login will be temporarily unavailable.

Good point 👍
I was undecided about including this. Thinking of it again I agree that it would help to avoid confusion and added a note with 01ab55f