Fix refcounting of gst_plugin_feature_load to match the docs.

Fix refcounting of gst_plugin_feature_load to match the docs.

Original commit message from CVS:
* gst/gstelementfactory.c: (gst_element_factory_create):
* gst/gstpluginfeature.c: (gst_plugin_feature_load):
* gst/gsttypefindfactory.c: (gst_type_find_factory_call_function):
* tools/gst-inspect.c: (print_element_info):
Fix refcounting of gst_plugin_feature_load to match the docs.
Fixes: #380129