Lazy load train information in the update UI

Ticket:	#6851
(cherry picked from commit 8fa0afd9c2d1067b3b3b3cfdd515f4299b4dfed6)
Add loading text and disable train select box while at it

Ticket:	#6851
(cherry picked from commit 45ffc77de6e1b8c6d52c8d874307517675800cce)