DeletePasswordJob with KWallet does not delete, but creates an empty entry instead

[Vogtinator]

I discovered this while looking at owncloud/client#9064

My theory is that

qtkeychain/keychain_unix.cpp

Line 520 in c729d0b

nextReply = iface->removeEntry( handle, q->service(), key, q->service() );

is never reached because mode is always either Text or Binary. That's a bug which owncloud-client could only work around by just not attempting to delete keys unfortunately.