feat: initial admin PAT has IAM_LOGIN_CLIENT (#10143)

# Which Problems Are Solved

We provide a seamless way to initialize Zitadel and the login together.

# How the Problems Are Solved

Additionally to the `IAM_OWNER` role, a set up admin user also gets the
`IAM_LOGIN_CLIENT` role if it is a machine user with a PAT.

# Additional Changes

- Simplifies the load balancing example, as the intermediate
configuration step is not needed anymore.

# Additional Context

- Depends on #10116 
- Contributes to https://github.com/zitadel/zitadel-charts/issues/332
- Contributes to https://github.com/zitadel/zitadel/issues/10016

---------

Co-authored-by: Stefan Benz <46600784+stebenz@users.noreply.github.com>

internal/api/grpc/system/instance.go

@@ -40,7 +40,7 @@ func (s *Server) GetInstance(ctx context.Context, req *system_pb.GetInstanceRequ
 }
 
 func (s *Server) AddInstance(ctx context.Context, req *system_pb.AddInstanceRequest) (*system_pb.AddInstanceResponse, error) {
-	id, _, _, details, err := s.command.SetUpInstance(ctx, AddInstancePbToSetupInstance(req, s.defaultInstance, s.externalDomain))
+	id, _, _, _, details, err := s.command.SetUpInstance(ctx, AddInstancePbToSetupInstance(req, s.defaultInstance, s.externalDomain))
 	if err != nil {
 		return nil, err
 	}
@@ -61,7 +61,7 @@ func (s *Server) UpdateInstance(ctx context.Context, req *system_pb.UpdateInstan
 }
 
 func (s *Server) CreateInstance(ctx context.Context, req *system_pb.CreateInstanceRequest) (*system_pb.CreateInstanceResponse, error) {
-	id, pat, key, details, err := s.command.SetUpInstance(ctx, CreateInstancePbToSetupInstance(req, s.defaultInstance, s.externalDomain))
+	id, pat, key, _, details, err := s.command.SetUpInstance(ctx, CreateInstancePbToSetupInstance(req, s.defaultInstance, s.externalDomain))
 	if err != nil {
 		return nil, err
 	}