No, it removes Conffiles, that's more than 2 characters of difference than "config files"
Conffiles at face value means any file explicitly listed as such by the packager, and while the intention is, in fact, to handle a program's settings I don't think it's expected to reach into user-specific configuration* and even less so into non-configuration "application data", with the distinction between the two not always being clear or practical to implement as you can see by comparing ~/.config with ~/.local !

* It's not particularly hard to implement something such as "rm -R .config/pizza from every user's home folder", but 1- I don't think there's a mechanism to declare that as conffiles, 2- it's not an unreasonable opinion that a package manager, aka "installing a program", should not affect user files

As for the original problem I'm not sure of the direct cause but:
- You can delete your keyring from ~/.local/share/keyrings/* (but of course it could be recreated by a program trying to use it to save passwords or the like)
- Getting the login keyring to unlock, if you actually wanted gnome-keyring, is done by a PAM module (check `sudo pam-auth-update`) and/or your Xsession (check, for Xfce, applications/settings/session&startup, both the individual autostart programs and the "launch Gnome services on startup")
- It doesn't work intentionally if you autologin, this can probably be changed by screwing around with PAM options but ain't nobody got time for that (so I also consider it a nuisance like policykit/logind/etc pushed by people who think PCs are commonly used simultaneously by different people...)
- Gajim may or may not support an alternative to gnome-keyring and kwallet (ie being its own password manager, like most browsers and email clients can)

Good luck!