[BUG] Fixed: if all group connection failed, E epoll event should be set on the group

[ethouris]

Also fixed the group-connection procedure insrt-test-live application in order to:

1. Wait for async connection, if non-blocking mode was set
2. Get the success or failure statement from the waiting function
3. Delete the configuration only when the link table is destroyed (immediate destruction would crash async connection).

[maxsharabayko]

To be merged with the [core] tags as of a higher priority to the [apps]