Different error messages when running empty workflow on all nodes or part of nodes

Fuel 10 #1338

Steps to reproduce:
  1. Log in to Fuel UI
  2. Go to 'Workflows' tab and add custom workflow without json file
  3. Go to 'Nodes' tab and add 2 controllers
  4. Go to 'Dashboard' tab and select Deployment Mode: Custom Workflow
  5. Press 'Run Workflow on 2 Nodes' button

You'll get the message 'There are no deployment tasks for graph type '123'. Checked cluster (ID=10), its plugins and release (ID=2).'

  6. Press Choose nodes (there is an arrow on the right side of 'Run Workflow on 2 nodes' button)
  7. Deselect 1 node
  8. Press 'Run Workflow on 1 of 2 Nodes' button

You'll get the message 'Deployment operation cannot be started. Nodes with uids [14] are not provisioned yet.'

Expected results:
  Messages coincide

Actual result:
  Seems that error messages do not correspond to actual errors, because if there is a workflow with tasks, then there is no message, that nodes are not provisioned.