Remove autoloader magic in registration.php

Unfortunately made it impossible to overload the autoloader and
magically set the custom autoloaders needed for the extension to
run. Thus I removed the registration.php file handled the magic.

This means regardless of using the .phar archive or phpstan-src
dependency, you have to manually configure the autoload.php
work-a-round in the project's phpstan configuration.

Author: shochdoerfer

composer.json

@@ -30,9 +30,6 @@
     "squizlabs/php_codesniffer": "^3.4"
   },
   "autoload": {
-    "files": [
-      "registration.php"
-    ],
     "psr-4": {
       "bitExpert\\PHPStan\\": "src/bitExpert/PHPStan"
     }