do not deprecate *host* macros support in "usermacro" API class

https://www.zabbix.com/documentation/6.4/en/manual/api/reference/usermacro

Says:

The host macro object is deprecated and will be removed in upcoming versions. Use the host.create and host.update methods to manage user macros on host level instead.

Consider please to not deprecate it or provide an alternative, as it's handy and is really used.