fix open port (Closes: #842541)

The open port is used for making keepass "single instance". It is used to send commands to a running keepass instance from the command line. It can e.g. trigger auto-type of a password. This is potentially invocable from any program running on the same system.

For any other actions that might be executed with this ipc interface, see: https://salsa.debian.org/felixdoerre-guest/keepass2/blob/a528ff9bba9e14280133d19416406e9c81e67e85/KeePass/Forms/MainForm_Functions.cs#L2910

I think it's best to just remove/deactivate this feature.