DB password prompt doesn't handle special characters properly

The issue was found by @piotrek during 1.14 sanity checks.

I'm using password with special characters both for my postgres user and db user. When calling:

$ rake unittest:backend

password is given but it looks like rake task doesn't escape special characters correctly, and the task fails.

Exporting env var e.g. $ export DB_MAINTENANCE_PASSWORD='***' and then calling the task helps.

I'm using GNU bash, version 5.1.16(1)-release (x86_64-pc-linux-gnu) as a shell.