Since just a single pointer is used to store the socket's GSource
if more than 1 consecutive request was done through the same
HTTP provider the 2nd request would clear the GSource associated to
the second request causing the 1st HTTP request to never complete
and end up in a expired timeout.

Use a hashtable instead so we can correctly track all requests.

https://bugzilla.redhat.com/show_bug.cgi?id=1821787

Fixes: 69f048bf ('cloud-setup: add tool for automatic IP configuration in cloud')