Fix Zoekt disk usage graph
This MR fixes the Persistent Volume Disk Utilization
dashboard. Currently, it uses ratios instead of percentages, which breaks the graph:
This is how the graph is going to look after the fix: thanos
Test Dashboard
$ ./test-dashboard.sh search/zoekt.dashboard.jsonnet
Installed https://dashboards.gitlab.net/dashboard/snapshot/q7aZWa0OsMNNStlG41IHfYKEXOGBju27 - search: Zoekt Info
https://dashboards.gitlab.net/dashboard/snapshot/q7aZWa0OsMNNStlG41IHfYKEXOGBju27
Edited by Dmitry Gruzd