[stable5] [backport] When reading the size of "files" mountpoints need to be excluded

Backport of ca57a84 from master to stable5.

The versions and trashbin app are now passing "includeMountPoints=false"
to "getFileInfo()" to make sure that the calculated total size doesn't
include mount points like Shared or external storage.

This is because the default call (legacy) used to return the size of
mount points as well.

Fixes #7755 

Please review @karlitschek @icewind1991 @schiesbn