B #6759: finalise the SG rules on sg rule error

instead of reseting the rules.
Open Nebula will raise and log the rule error for further investigation, but the VM will not be left unprotected.

src/vnm_mad/remotes/lib/sg_driver.rb

@@ -125,7 +125,7 @@ def activate(do_all = false)
                         sg.run!
                     rescue StandardError => e
                         unlock
-                        deactivate(do_all)
+                        SGIPTables.nic_post(@vm, nic)
                         raise e
                     end
                 end