fix: P8a blocks Theme Builder layouts without Divi's theme_builder role (L6)

et_header_layout, et_body_layout, et_footer_layout and et_template showing a
global entry now block a confirmed edit unless et_pb_is_allowed('theme_builder'),
like Divi's own check for TB layouts.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

tests/Support/LibraryFixtures.php

@@ -123,7 +123,7 @@ final class LibraryFixtures
         Functions\when('_get_non_cached_ids')->returnArg(1);
         Functions\when('_prime_post_caches')->justReturn(null);
         Functions\when('wp_cache_delete')->justReturn(true);
-        $usages = Mockery::mock(GlobalUsages::class, [null, $roles])->makePartial();
+        $usages = Mockery::mock(GlobalUsages::class, [null, $roles ?? self::roles()])->makePartial();
         $usages->allows('rows')->andReturnUsing(static fn (): array => is_array($rows) ? $rows : $rows());
 
         return $usages;