install-script,autoyast: Adjust base patterns for Leap 15.3 & don't try to set the user's avatar

Leap 15.3 has adopted the same base patterns as tumbleweed, dropping apparmor_opt and enhanced_base_opt patterns.

Fixes: #76 (closed)

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Setting the user's avatar is causing issues when using an OS with a different language than English (es_ES, in my case).

The error reported is:

Language 'es_ES.UTF-8' was not found within the list of supported
languages avaiable at /usr/share/YaST2/data/languages.

Fallback language en_US will be used.

This led me to think that the problem could be in the language we set for the system, but after several tests I found out that no, it was not.

Removing the bits related to the user avatar solves the issue.

Fixes: #77 (closed)