Remove obsolete CSS text classes (#30576)

- `.text-thin` and `.text-italic` are not present in CSS so were doing nothing and I removed them.
- `.text.middle` was unused so I removed it.
- `.text.italic` is replaced with `tw-italic`.
- `.text.normal` had exactly one use and it wasn't even needed.
- add a `muted` class to the link to `org_profile_avatar.tmpl`.

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Co-authored-by: wxiaoguang <wxiaoguang@gmail.com>

templates/shared/user/org_profile_avatar.tmpl

@@ -4,7 +4,7 @@
 			<div class="column">
 				<div class="ui header tw-flex tw-items-center gt-word-break">
 					{{ctx.AvatarUtils.Avatar . 100}}
-					<span class="text thin grey"><a href="{{.HomeLink}}">{{.DisplayName}}</a></span>
+					<span class="text grey"><a class="muted" href="{{.HomeLink}}">{{.DisplayName}}</a></span>
 					<span class="org-visibility">
 						{{if .Visibility.IsLimited}}<div class="ui medium basic horizontal label">{{ctx.Locale.Tr "org.settings.visibility.limited_shortname"}}</div>{{end}}
 						{{if .Visibility.IsPrivate}}<div class="ui medium basic horizontal label">{{ctx.Locale.Tr "org.settings.visibility.private_shortname"}}</div>{{end}}