R1:6036079e883a

PHP 8.2: fix deprecated use of "parent" in callables

Summary: Closes T15200

Test Plan:
Test 1:

I was able to run `arc unit --everything` without the error thrown from T15200

Test 2:

I also tried this and it still works:

```
php -a
require 'src/applications/metamta/exception/PhabricatorMetaMTAReceivedMailProcessingException.php';
$asd = new PhabricatorMetaMTAReceivedMailProcessingException("1", "TEST MESSAGE");
var_dump($asd->getMessage());
```

You get:

```
string(12) "TEST MESSAGE"
```

Reviewers…