Removed use function imports for mocked/stubbed functions, disabling phpcs import rule

While the rule is now disabled, it still is very much valuable to import most pure functions from the core
PHP scope, allowing us some marginal gains on anything that can be inlined by the engine (now or in future).

The rule does not allow selective exclusions, so we will need to keep it off for now.

src/Provider/Dce/SystemDceSecurityProvider.php

@@ -18,11 +18,8 @@ use Ramsey\Uuid\Exception\DceSecurityException;
 use Ramsey\Uuid\Provider\DceSecurityProviderInterface;
 use Ramsey\Uuid\Type\IntegerValue;
 
-use function constant;
 use function escapeshellarg;
-use function ini_get;
 use function preg_split;
-use function shell_exec;
 use function str_getcsv;
 use function strpos;
 use function strrpos;