Don't pre-install cryfs and encfs

These were formerly supported as encryption backends for Plasma Vaults.
Nowadays only gocryptfs is supported for new vaults, though the other two
remain supported for compatibility with older vaults, so it can be nice
to keep them around.

However anyone migrating to KDE Linux needs to do a re-install anyway,
and if they migrate their data, they'll have to do it manually. Thus
it's reasonable for anyone who's enough of an expert to accomplish this
to migrate any old vaults they have to the supported gocryptfs backend.

Thus, get rid of the two legacy backends.

---

Bonus commit: stop asking for gocryptfs explicitly, since it's a mandatory dependency of plasma-vaults and thus gets pulled in automatically

mkosi.conf.d/20-packages-middleware.conf

@@ -54,10 +54,7 @@ Packages=
     bluez-obex # Bluetooth file sharing, through the KCM
     bup # kup, for one of the backends
     catdoc # kfilemetadata, for indexing old MS word docs
-    cryfs # plasma-vault, for compatibility
-    encfs # plasma-vault, for compatibility
     fwupd # for Discover backend
-    gocryptfs # plasma-vault, for new vaults
     jxrlib # kimageformats
     libappimage # kio-extras, for AppImage app thumbnails
     libappindicator-gtk3 # plasma-desktop, for tray icon support in GTK 3 apps