Right now when there is more than one file item action, all of them get
dumped into a sub-menu. Because both Konsole and Gwenview install
plugins, and most Plasma installations include these apps, most users
experience the file item action plugins in sub-menu form.

Using a sub-menu when there is more than one item feels a bit excessive.
Showing up to three inline should avoid bloating the menu too much while
still handling the rare cases when there are tons and tons of items

BUG: 424281
FIXED-IN: 5.73