Site Health: Remove unnecessary function_exists() checks from WP_Site_Health::get_tests().

By the time the tests run, both `wp_is_site_protected_by_basic_auth()` and `rest_url()` functions are available, so there is no need to check for their existence.

Follow-up to [44986], [51057].

Props Clorith, costdev, SergeyBiryukov.
Fixes #52642.

git-svn-id: https://develop.svn.wordpress.org/trunk@51066 602fd350-edb4-49c9-b593-d223f7449a82

Author: SergeyBiryukov

src/wp-admin/includes/class-wp-site-health.php

@@ -2310,6 +2310,11 @@ public static function get_tests() {
 					'label' => __( 'HTTP Requests' ),
 					'test'  => 'http_requests',
 				),
+				'rest_availability'         => array(
+					'label'     => __( 'REST API availability' ),
+					'test'      => 'rest_availability',
+					'skip_cron' => true,
+				),
 				'debug_enabled'             => array(
 					'label' => __( 'Debugging enabled' ),
 					'test'  => 'is_in_debug_mode',
@@ -2352,23 +2357,12 @@ public static function get_tests() {
 		);
 
 		// Conditionally include Authorization header test if the site isn't protected by Basic Auth.
-		if ( function_exists( 'wp_is_site_protected_by_basic_auth' ) ) {
-			if ( ! wp_is_site_protected_by_basic_auth() ) {
-				$tests['async']['authorization_header'] = array(
-					'label'     => __( 'Authorization header' ),
-					'test'      => rest_url( 'wp-site-health/v1/tests/authorization-header' ),
-					'has_rest'  => true,
-					'headers'   => array( 'Authorization' => 'Basic ' . base64_encode( 'user:pwd' ) ),
-					'skip_cron' => true,
-				);
-			}
-		}
-
-		// Conditionally include REST rules if the function for it exists.
-		if ( function_exists( 'rest_url' ) ) {
-			$tests['direct']['rest_availability'] = array(
-				'label'     => __( 'REST API availability' ),
-				'test'      => 'rest_availability',
+		if ( ! wp_is_site_protected_by_basic_auth() ) {
+			$tests['async']['authorization_header'] = array(
+				'label'     => __( 'Authorization header' ),
+				'test'      => rest_url( 'wp-site-health/v1/tests/authorization-header' ),
+				'has_rest'  => true,
+				'headers'   => array( 'Authorization' => 'Basic ' . base64_encode( 'user:pwd' ) ),
 				'skip_cron' => true,
 			);
 		}