Reduce Jetpack Admin page queries for connected users.

[dereksmart]

Changes proposed in this Pull Request:

Related to #13463, we are unnecessarily passing the build_connect_url value on every page load of the Jetpack admin. The historical reason for this, is that we used to not reload the page after disconnecting. However, since the new full-screen modal required a page load after disconnect, we can be smarter about when we use the resources to build the url only when we need it.

It prevents about 6-7 unnecessary queries when the current user is connected.

Is this a new feature or does it add/remove features to an existing part of Jetpack?

• Faster Jetpack admin page load?

Testing instructions:

Check out query monitor or something similar. Note the queries for a connected user on page load of the main Jetpack Admin dashboard.

Check it out with the patch applied as a connected user. There should be way fewer queries.

Functional testing:
0. From the main Jetpack dashboard:

• Connect the site to wordpress.com. There should be no problem.
• Disconnect, and then reconnect. There should be no problem.
• Create a secondary user while the site is connected.
• Visit the Jetpack admin page, and click to "create account" as that secondary user. There should be no problem.

Proposed changelog entry for your changes:

• Faster Jetpack admin page load?

[jetpackbot]

Thank you for the great PR description!

When this PR is ready for review, please apply the [Status] Needs Review label. If you are an a11n, please have someone from your team review the code if possible. The Jetpack team will also review this PR and merge it to be included in the next Jetpack release.

Scheduled Jetpack release: October 1, 2019.
Scheduled code freeze: September 24, 2019

Generated by 🚫 dangerJS against 16968a6

[jeherve]

Looking good! Merging.