[applet] Restore former default action
The default was changed in the ExpandibleListItem port to "Open with file manager" in the interests of having better defaults, but this change was ill-considered for the following reasons:
- It left no way to only open the vault without also opening a file manager, which apparently is a real and valid use case
- The "Open with file manager" item in the expanded view became totally redundant
I still think that opening in the file manager is a better default, but that change needs to be done properly, and doing so requires string and icon changes and further adjustments in the applet which are not suitable for 5.19. So for now, let's revert to the pre-5.19 behavior to unbreak people.
BUG: 422917 FIXED-IN: 5.19.1