numbercategorymodel: fix logic
numbercategorymodel: fix logic

The "Other" category was not created properly but was more a "side-effect".
NumberCategoryModel::other() method was broken, and the "Other" category was
added in NumberCategoryModel::addCategory if the specified category was empty.

This commits fixes that and three minors issues:

- proper line width
- inverse faulty if condition
- replace layoutChanged signal by more accurate one

Issue: #78188
Change-Id: I58a524880d460972ee57f455d4c70f525d91491e

savoirfairelinux/ring-lrc,savoirfairelinux/ring-lrc,savoirfairelinux/ring-lrc,savoirfairelinux/ring-lrc,savoirfairelinux/ring-lrc