In the OVF template, we have the password option, which should be used to configure the password for the vyos user.
During Cloud-init run this option is saved to the cloud-config, unlike other parameters from the OVF file, which goes directly to the metadata. So, to get a password, the cc_vyos module should check the cfg dict.
In the decb5d2 commit a way to add password-based authentication was changed to a per-user basis. And the cc_vyos now able to use only passwords from users' configurations.

Therefore, OVA builds after 2020-09-10 ignore the password field.