Disable defer JS in Divi builder

[haqadn]

Fixes HOG-399

Proposed changes:

• Skip deferring JS if we are inside Divi builder.

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

None

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

No

Testing instructions:

A12s: You can also use the test site mentioned in HOG-399.

• Enable deferred JS in Boost.
• Install Divi 5.
• Go to Divi > Theme Builder.
• We need to get into the Divi builder now, Since you don't likely have any existing templates, you can click Add Global Header -> Build Global Header:

This should take you to the builder.

• Using Boost Debugger extension, make sure deferred JS is not working.

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[jp-launch-control]

Code Coverage Summary

Coverage changed in 1 file.

File	Coverage	Δ%	Δ Uncovered
projects/plugins/boost/jetpack-boost.php	0/116 (0.00%)	0.00%	1 ❤️‍🩹

1 file is newly checked for coverage.

File	Coverage
projects/plugins/boost/compatibility/divi.php	0/18 (0.00%) 💔

Full summary · PHP report · JS report

_{If appropriate, add one of these labels to override the failing coverage check: Covered by non-unit tests Use to ignore the Code coverage requirement check when E2Es or other non-unit tests cover the code Coverage tests to be added later Use to ignore the Code coverage requirement check when tests will be added in a follow-up PR I don't care about code coverage for this PR Use this label to ignore the check for insufficient code coveage.}