Chronograf - static legend: alias for shown value name




I´m new to the TICK Stack but i know Grafana and Prometheus1+2 so far.
As a devops engineer i started to test the TICK stack and found out, that the static legend is not so cute like in Grafana.
For example i have a graph with the following metric:
SELECT mean(“used_percent”) AS " " FROM “telegraf”.“autogen”.“disk” WHERE time > :dashboardTime: GROUP BY time(:interval:), “host” FILL(null)
Now i found out, that i can set aliases with “AS” to any metric but the problem is, that i have still standing [host=server1]. I want to delete “[host=]” and the “]” at the end.
Here you can watch how it is shown now:

How can i only show the name of any server in the legend?
I don´t need info about which metric is that, because i have several graphs for every metric.

Best regards,