Fix MM-54027 (#24495)

* Fix MM-54027

* Add tests

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/channels/app/authorization.go

@@ -404,5 +404,8 @@ func (a *App) SessionHasPermissionToManageBot(session model.Session, botUserId s
 }
 
 func (a *App) HasPermissionToReadChannel(c request.CTX, userID string, channel *model.Channel) bool {
+	if !*a.Config().TeamSettings.ExperimentalViewArchivedChannels && channel.DeleteAt != 0 {
+		return false
+	}
 	return a.HasPermissionToChannel(c, userID, channel.Id, model.PermissionReadChannelContent) || (channel.Type == model.ChannelTypeOpen && a.HasPermissionToTeam(userID, channel.TeamId, model.PermissionReadPublicChannel))
 }