The loading progress would not be reset upon failure, causing issues
when you tried to start loading again.
Bug: T96437
Change-Id: I7ec4be82304c101fa1bd634f60bc6b0047e2d53d
Collapsible relates to the Vector menu behaviour where an item
is moved into the dropdown menu if the window is narrow.
This should only apply to the secondary tab when there are two tabs.
If there is only one tab (non-VE, e.g. in a non-VE namespace) then
this tab should not be collapsible.
Server-side code handled this correctly, but client-side was
adding the class unconditionally.
Change-Id: Iecd195e92f43fe9f11b3938a1a24caed7b331e5f
