Fix errcheck issues in server/channels/app/login_test (#29119)

Co-authored-by: Ben Schumacher <ben.schumacher@mattermost.com>

server/.golangci.yml

@@ -101,7 +101,6 @@ issues:
         channels/app/integration_action.go|\
         channels/app/integration_action_test.go|\
         channels/app/job_test.go|\
-        channels/app/login_test.go|\
         channels/app/migrations.go|\
         channels/app/permissions.go|\
         channels/app/permissions_test.go|\