Remove unnecessary helper methods

[tdauth]

If the following methods are not used anywhere, remove them:

trait GuiStateMachine {
  def getAllExploredActions: Set[Action]
  def getActionExecutionTime: Map[Action, Int]
}

They have only been added due to legacy code.

Then we can use a TrieMap or concurrent hash map for the states and remove synchronized.

We can also remove the execution counter for the action transitions and use a TrieMap here, too.