Prevent issues reordering in Epics when on mobile

In Sub-Epics and Issues can ordered by dragging and dropping then directly on the web page. But when browsing Epics on mobile, they usually take the full width of the page, which makes scrolling difficult. It leads to often reorder them by mistake. Worse, it's impossible to undo the re-ordering. So if the user didn't see what happened on the screen (under their finger), they can't restore the order manually for sure.

Proposal

Disable re-ordering completely on mobile. This is usually not an operation done via the medium. Mobile is often used only for consultation and comments. I don't even think we need to provide an option to enable the reorder on mobile.

Related: !89161 (merged)