domain: Remove unneeded *_handle functions

Not needed now that we properly do cleanup

src/virtManager/connection.py

@@ -745,7 +745,6 @@ class vmmConnection(vmmGObject):
     def rename_vm(self, domainobj, origxml, newxml):
         # Undefine old domain
         domainobj.delete()
-        domainobj.release_handle()
 
         newobj = None
         try:

src/virtManager/domain.py

@@ -234,14 +234,6 @@ class vmmDomain(vmmLibvirtObject):
     def get_install_abort(self):
         return bool(self._install_abort)
 
-    def set_handle(self, vm):
-        self._backend = vm
-    def release_handle(self):
-        del(self._backend)
-        self._backend = None
-    def get_handle(self):
-        return self._backend
-
     def enable_unsupported_rhel_opts(self):
         if not self.is_libexec_qemu():
             return True

src/virtManager/network.py

@@ -60,10 +60,6 @@ class vmmNetwork(vmmLibvirtObject):
     def _define(self, xml):
         return self.get_connection().vmm.networkDefineXML(xml)
 
-
-    def set_handle(self, net):
-        self.net = net
-
     def set_active(self, state):
         self.active = state