PHP unit tests: remove WP_RUN_CORE_TESTS const (#65631)

Co-authored-by: ramonjd <ramonopoly@git.wordpress.org>
Co-authored-by: andrewserong <andrewserong@git.wordpress.org>

phpunit/bootstrap.php

@@ -24,12 +24,6 @@
 define( 'GUTENBERG_DIR_TESTDATA', __DIR__ . '/data/' );
 define( 'GUTENBERG_DIR_TESTFIXTURES', __DIR__ . '/fixtures/' );
 
-// Pretend that these are Core unit tests. This is needed so that
-// wp_theme_has_theme_json() does not cache its return value between each test.
-if ( ! defined( 'WP_RUN_CORE_TESTS' ) ) {
-	define( 'WP_RUN_CORE_TESTS', true );
-}
-
 // Require composer dependencies.
 require_once dirname( __DIR__ ) . '/vendor/autoload.php';