A4A Client: Only show disconnect dialog during plugin deactivation when connected

[nateweller]

Fixes https://github.com/Automattic/automattic-for-agencies-dev/issues/348

Proposed changes:

• Checks if the site is connected before adding the deactivation handler that prompts to disconnect the site during plugin deactivation.

Other information:

• Have you written new tests for your changes, if applicable?
• Have you checked the E2E test CI results, and verified that your changes do not break them?
• Have you tested your changes on WordPress.com, if applicable (if so, you'll see a generated comment below with a script to run)?

Jetpack product discussion

https://github.com/Automattic/automattic-for-agencies-dev/issues/348

Does this pull request change what data or activity we track or use?

No

Testing instructions:

• Spin up a JN site with the A4A client plugin installed.
• With a disconnected site, deactivate the plugin. Verify no interstitial connection pop-up is shown and the plugin deactivates right away.
• Re-activate the plugin, and connect the site.
• Deactivate the plugin, verify the disconnect dialog pops up before deactivating the plugin.

[github-actions]

Thank you for your PR!

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Automattic For agencies client plugin:

• Next scheduled release: June 4, 2024.
• Scheduled code freeze: May 27, 2024.

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[andrii-lysenko]

This makes sense to me and works as described 👍

[gogdzl]

LGTM!