create_connection fails to find the created connection if network-manager doesn't detect it quickly enough

This is a problem I thought we solved before but apparently not, since it's hitting quite a few systems which are running the tests in our labs.

Basically the create_connection script runs 'nmcli con up' to try and bring up the newly created connection. This allows it to be sure that the connection is ready to use. It seems though that network-manager can be a little slow with actually registering the connection so that it appears to nmcli. I think we need to add a time delay between each retry, otherwise the script just jumps through the attempts in rapid succession, and exits without any certainty of a proper connection being active.