Fix more of uninitialized struct user_pass local vars

Fix more of uninitialized struct user_pass local vars

Not all of these touch uninitialzed members of the struct, but that
could change in future.

Change-Id: I71bc847b48da54b70f60ccd7c4521ec699daf9cb
Signed-off-by: Selva Nair <selva.nair@gmail.com>
Acked-by: Gert Doering <gert@greenie.muc.de>
Message-Id: <20240909204829.10379-1-selva.nair@gmail.com>
URL: https://www.mail-archive.com/openvpn-devel@lists.sourceforge.net/msg29152.html
Signed-off-by: Gert Doering <gert@greenie.muc.de>
(cherry picked from commit aa1dd09b5fc196499c84d2ef9b0c254ebb1745d8)