bug#40087: custom zabbix alert scripts are expected to be found in /gnu/store

[Ricardo Wurmus]

I added a new script “media type” in Zabbix and specified that the
script to be run should be /srv/my-script.

When testing an action for this media type, Zabbix attempts to find the
script in the /share/zabbix/alertscripts directory of the zabbix-server
package:

    Cannot execute command 
"/gnu/store/vic3bhg8jjws4gv9ivzrn8i4vnxd5nf3-zabbix-server-4.4.1/share/zabbix/alertscripts//srv/my-script":
 [2] No such file or directory

This means that custom Zabbix alert scripts don’t work.

--
Ricardo