3. Await bus read blocking bus read in Gstd - Callback issue

[carlos-aguero]

Issue reported by @mleivaf

[tvlenin]

Modifying the value of keep_connection_open.

- keep_connection_open = 0: gstc_pipeline_bus_wait_async works but the message is not received. - keep_connection_open = 1: gstc_pipeline_bus_wait_async don't works. Does not allow creating a new connection with gstd.