Migrate the telemetry endpoint to use REST API

[itsmeichigo]

Closes: #8646

Description

This PR continues the REST API migration work by enabling the send telemetry endpoint to use the REST API.

Testing instructions

Pre-requisite: due to a rate-limit issue with Pressable sites, create a JN site to ensure that testing is smooth for now.

• Enable feature flag applicationPasswordAuthenticationForSiteCredentialLogin and build the app.
• Log out of the app or skip onboarding if needed.
• On the prologue screen, select Enter your site address and enter the address of your self-hosted site.
• Proceed to log in with site credentials.
• When the login succeeds, you should see the home screen.
• Suppose your test store has Woo version >= 5.9.0, you should be able to see a log in the Xcode console: Successfully sent telemetry for siteID (unless throttled).
• Please feel free to install Woo version < 5.9.0 and repeat the steps above. Telemetry API is not available for these versions so the request should not be made.

Screenshots

N/A

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

[wpmobilebot]

You can test the changes from this Pull Request by:

• Clicking here or scanning the QR code below to access App Center
• Then installing the build number pr8647-3c3e415 on your iPhone

If you need access to App Center, please ask a maintainer to add you.

[jaclync]

LGTM

[jaclync]

Do we want to also add test cases for TelemetryRemoteTests?

[itsmeichigo]

Added a new case in 3c3e415.