test: move test not requiring internet from internet to parallel

test-dgram-send-cb-quelches-error works with or without a network. Move
to `parallel` directory.

PR-URL: #30545
Reviewed-By: Anna Henningsen <anna@addaleax.net>
Reviewed-By: Colin Ihrig <cjihrig@gmail.com>
Reviewed-By: Luigi Pinca <luigipinca@gmail.com>

Author: Trott