Skip $db parameter in query

Author: anahan

src/JaegerMongoDbCommandConvertor.php

@@ -140,6 +140,7 @@ public function convert(object $command): string
         $result = 'db.runCommand({';
         foreach ($command as $k => $v) {
             switch ($k) {
+                case '$db':
                 case 'lsid':
                 case 'txnNumber':
                     continue 2;