fix: tag GELF handler with _keboola_owned for proper cleanup

The GELF handler added in set_gelf_logger was not tagged, so the
cleanup loop (which only removes _keboola_owned handlers) left it on
the root logger when set_default_logger or set_gelf_logger was called
again, causing duplicate log delivery.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Author: matyas-jirat-keboola

src/keboola/component/interface.py

@@ -220,6 +220,7 @@ def set_gelf_logger(log_level: int = logging.INFO, transport_layer='TCP',
         else:
             raise ValueError(F'Unsupported gelf transport layer: {transport_layer}. Choose TCP or UDP')
 
+        gelf._keboola_owned = True
         logging.getLogger().setLevel(log_level)
         logging.getLogger().addHandler(gelf)