Fix pass by reference PHP warnings due to PHP 4 compatibility hacks inherited from Core

[tomjn]

This closes #19403 and eliminates a PHP 4.x compatibility fix that causes problems

This fixes a number of PHP warnings. The styles and scripts objects don't need to be passed by reference, that's the default behaviour of objects in PHP 5.0+, the references are only there to avoid object duplication in PHP 4.0 which used pass by value semantics for objects, unlike 5.0 which switched to pass by reference.

How has this been tested?

I made the adjustment locally and the problems went away, no issues were introduced

Types of changes

Bug fix (non-breaking change which fixes an issue)

Checklist:

• My code is tested.
• My code follows the WordPress code style.
• My code follows the accessibility standards.
• My code has proper inline documentation.
• I've included developer documentation if appropriate.
• I've updated all React Native files affected by any refactorings/renamings in this PR. .

[earnjam]

Looks like a duplicate PR was merged two weeks ago with #21987, so I'm going to close this one out.