BUGFIX: Catch stderr output, in case phpPathAndBinary is not found

previously on windows:

```
.\flow.bat configuration:show
Das System kann den angegebenen Pfad nicht finden.
Das System kann den angegebenen Pfad nicht finden.

  Type: Neos\Flow\Core\Booting\Exception\SubProcessException
  Code: 1355480641
  File: Packages\Framework\Neos.Flow\Classes\Core\Booting\Scripts.php
  Line: 716

Open Data/Logs/Exceptions/20230715100927f65665.txt for a full stack trace.
```

notice the duplicated echo'd `Das System kann den angegebenen Pfad nicht finden.`

afterwards, the first echo will be gone.

Neos.Flow/Classes/Core/Booting/Scripts.php

@@ -835,7 +835,7 @@ protected static function ensureCLISubrequestsUseCurrentlyRunningPhpBinary($phpB
         }
 
         // Try to resolve which binary file PHP is pointing to
-        exec($phpBinaryPathAndFilename . ' -r "echo realpath(PHP_BINARY);"', $output, $result);
+        exec($phpBinaryPathAndFilename . ' -r "echo realpath(PHP_BINARY);" 2>&1', $output, $result);
         if ($result === 0 && sizeof($output) === 1) {
             // Resolve any wrapper
             $configuredPhpBinaryPathAndFilename = $output[0];
@@ -879,7 +879,7 @@ protected static function ensureWebSubrequestsUseCurrentlyRunningPhpVersion($php
             return;
         }
 
-        exec($phpCommand . ' -r "echo PHP_VERSION;"', $output, $result);
+        exec($phpCommand . ' -r "echo PHP_VERSION;" 2>&1', $output, $result);
 
         if ($result !== 0) {
             return;