Coding Standards: Adjust coding standards to always omit parentheses for...

Coding Standards: Adjust coding standards to always omit parentheses for `include`/`require` statements.

These are language constructs, not function calls, so the parentheses are unnecessary.

This updates the PHPCS configuration file the enforce the sniff until it is moved from the `WordPress-Extra` ruleset to the `WordPress-Core` ruleset upstream.

Follow-up to [47198].

Props desrosj, jrf, GaryJ.
Fixes #49376.
Built from https://develop.svn.wordpress.org/trunk@47207


git-svn-id: https://core.svn.wordpress.org/trunk@47007 1a063a9b-81f0-0310-95a4-ce76da25c4cd