Use core's disconnect hook

Support for disconnecting after an operation is now in the core, so
there is no need to copy-paste the whole with_provider_connection
function anymore.

app/models/manageiq/providers/redhat/infra_manager/api_integration.rb

@@ -101,20 +101,10 @@ def ovirt_services(args = {})
                         end
   end
 
-  def with_provider_connection(options = {})
-    raise "no block given" unless block_given?
-    _log.info("Connecting through #{self.class.name}: [#{name}]")
-    begin
-      connection = connect(options)
-      yield connection
-    ensure
-      begin
-        self.class.disconnect(connection)
-      rescue => error
-        _log.error("Error while disconnecting #{error}")
-        nil
-      end
-    end
+  def disconnect(connection)
+    self.class.disconnect(connection)
+  rescue StandardError => error
+    _log.error("Error while disconnecting #{error}")
   end
 
   def verify_credentials_for_rhevm(options = {})