Debian: make admin account mandatory

I'm on Debian testing and folled followed the installation steps of a single node instance. Then I was at the admin account step. the screen says:

> If this field is left blank, an admin user will not be created.

I thought (not having used CouchDB in many years), yay, I just want Admin-Party mode. But then I saw an error that CouchDB wouldn't start up correctly:

> WARNING: Unable to create standalone system databases.
> CouchDB may not have started correctly (no init?)

Checking the logs reveal:

> No Admin Account Found, aborting startup.
> Please configure an admin account in your local.ini file.

Hence I propose making the admin password mandatory as I don't see a reason why someone wouldn't want to set a password and then set it later manually.

Start by reproducing the Debian testing single-node installation and inspect the admin-account step described in the issue. Trace how a blank value is handled in local.ini and verify that the installer requires an admin password, while a configured account allows CouchDB to start without the reported warning.

Written by the indexing model from the issue text.