server: minor cleanup of logging around draining

This commit moves the "drain succeeded" logging message to be at the
very end of the drain process. Also, it removes now stale comment.

Release note: None

Author: yuzefovich

pkg/server/drain.go

@@ -447,10 +447,6 @@ func (s *drainServer) drainClients(
 	// tasks that may issue SQL statements have shut down.
 	s.sqlServer.leaseMgr.SetDraining(ctx, true /* drain */, reporter)
 
-	// Mark this phase in the logs to clarify the context of any subsequent
-	// errors/warnings, if any.
-	log.Infof(ctx, "SQL server drained successfully; SQL queries cannot execute any more")
-
 	session, err := s.sqlServer.sqlLivenessProvider.Release(ctx)
 	if err != nil {
 		return err
@@ -464,8 +460,9 @@ func (s *drainServer) drainClients(
 
 	// Mark the node as fully drained.
 	s.sqlServer.gracefulDrainComplete.Set(true)
-
-	// Done. This executes the defers set above to drain SQL leases.
+	// Mark this phase in the logs to clarify the context of any subsequent
+	// errors/warnings, if any.
+	log.Infof(ctx, "SQL server drained successfully; SQL queries cannot execute any more")
 	return nil
 }