fix: Cannot declare class CodeIgniter\Config\Services, because the name is already in use

See codeigniter4#8745 (comment)

Author: kenjis

system/Config/BaseService.php

@@ -389,8 +389,15 @@ protected static function buildServicesCache(): void
                 $locator = static::locator();
                 $files   = $locator->search('Config/Services');
 
+                $systemPath = static::autoloader()->getNamespace('CodeIgniter')[0];
+
                 // Get instances of all service classes and cache them locally.
                 foreach ($files as $file) {
+                    // Does not search `CodeIgniter` namespace to prevent from loading twice.
+                    if (str_starts_with($file, $systemPath)) {
+                        continue;
+                    }
+
                     $classname = $locator->findQualifiedNameFromPath($file);
 
                     if ($classname === false) {