Before this commit, avatar of operator was not displayed properly. This is due to src of avatar being wrongly computed: the serverUrl data is in `PublicLivechatGlobal`, not in `LivechatButtonView`. Because of this, the src was prefixed with `undefined/` instead of the server url, hence no displaying the avatar of operator. This commit fixes issue by getting actual `serverUrl` in correct model `PublicLivechatGlobal`. closes odoo/odoo#99022 Signed-off-by: Sébastien Theys (seb) <seb@odoo.com>