fix: Correctly inherit the Composer restarted process settings

> [!WARNING]
> Note: this PR is more of draft. I am not confident I understand fully
the issue neither that this is the right fix (and I could not test it).
Do NOT assume this code just works.

After a lot of digging in box-project/box#988,
@maartendekeizer could identify the root of the issue.

My understanding is that Flex tries to detect if the current PHP process
was restarted by Composer and forwards its restarted settings to the
sub-processes it is going to launch. There is currently two things done:

- symfony#91 which if took code from SensioDistributionBundle.
- symfony#899 which kind of followed the suite.

    I suspect the mentioned code predates `composer/xdebug-handler`. Now
with this package, there is two things to take into account:

- The `composer/xdebug-handler` API is likely much safer, more robust
  and a lot less hacky to use.
- There is other applications that can restart a PHP process. As an
  example Box restarts the PHP process to be able to correct the
`phar.readonly` setting that cannot be changed at runtime. It matters as
the restarted process by be executing a Composer command.

As mentioned in the warning, I could not test this, not even run the
tests locally, so I would be careful about this PR. I just wanted to
give a base about a potential fix with context about the original issue
encountered.

On my side to not have to wait on Flex and avoid the users to have to
update it to have the fix, Box launches its Composer commands with
`COMPOSER_ORIGINAL_INIS=''` to avoid Flex to trigger this bad piece of
code.

src/ScriptExecutor.php

@@ -16,6 +16,7 @@
 use Composer\IO\IOInterface;
 use Composer\Semver\Constraint\MatchAllConstraint;
 use Composer\Util\ProcessExecutor;
+use Composer\XdebugHandler\PhpConfig;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Output\StreamOutput;
 use Symfony\Component\Process\PhpExecutableFinder;
@@ -116,20 +117,8 @@ private function expandPhpScript(string $cmd, array $scriptArguments): string
 
         $arguments = $phpFinder->findArguments();
 
-        if ($env = (string) getenv('COMPOSER_ORIGINAL_INIS')) {
-            $paths = explode(\PATH_SEPARATOR, $env);
-            $ini = array_shift($paths);
-        } else {
-            $ini = php_ini_loaded_file();
-        }
-
-        if ($ini) {
-            $arguments[] = '--php-ini='.$ini;
-        }
-
-        if ($memoryLimit = (string) getenv('COMPOSER_MEMORY_LIMIT')) {
-            $arguments[] = "-d memory_limit={$memoryLimit}";
-        }
+        $phpConfig = new PhpConfig();
+        $phpConfig->usePersistent();
 
         $phpArgs = implode(' ', array_map([ProcessExecutor::class, 'escape'], $arguments));
         $scriptArgs = implode(' ', array_map([ProcessExecutor::class, 'escape'], $scriptArguments));