Config: remove some more output buffering

I don't see why output buffering is needed here.
The `DeepExitException` accepts/allows an empty string as the "message", so there is no reason to collect the screen output via buffering first, only to echo it out again as soon as the exception is caught (by the `Runner`) class.

Author: jrfnl

src/Config.php

@@ -679,11 +679,8 @@ public function processShortArgument($arg, $pos)
         switch ($arg) {
         case 'h':
         case '?':
-            ob_start();
             $this->printUsage();
-            $output = ob_get_contents();
-            ob_end_clean();
-            throw new DeepExitException($output, 0);
+            throw new DeepExitException('', 0);
         case 'i' :
             ob_start();
             Standards::printInstalledStandards();
@@ -796,11 +793,8 @@ public function processLongArgument($arg, $pos)
     {
         switch ($arg) {
         case 'help':
-            ob_start();
             $this->printUsage();
-            $output = ob_get_contents();
-            ob_end_clean();
-            throw new DeepExitException($output, 0);
+            throw new DeepExitException('', 0);
         case 'version':
             $output  = 'PHP_CodeSniffer version '.self::VERSION.' ('.self::STABILITY.') ';
             $output .= 'by Squiz and PHPCSStandards'.PHP_EOL;