[MM-31360] downgrade error logs which doesn't break the flow (#16612)

* downgrade error logs which doesn't break the flow

* reflect revivew comments

api4/channel.go

@@ -212,7 +212,7 @@ func updateChannel(c *Context, w http.ResponseWriter, r *http.Request) {
 
 	if oldChannelDisplayName != channel.DisplayName {
 		if err := c.App.PostUpdateChannelDisplayNameMessage(c.App.Session().UserId, channel, oldChannelDisplayName, channel.DisplayName); err != nil {
-			mlog.Error(err.Error())
+			mlog.Warn("Error while posting channel display name message", mlog.Err(err))
 		}
 	}