Dashbord import replace $DS_PROMETHEUS to hardcoded value when import via web ui but not when do it by code.

### What happened? I use Grafana 9.1.5 provisioned by rancher-monitoring chart. Then I have a dashboard installed by chart by using gnetId: 11835 (redis). Then when I take the json of this dashboard and import it manually I notice odd bug. So the dashbord has a reference to datasource by using variable: "datasource": "${DS_PROMETHEUS}" Then for the dashbord imported by gnetid all is fine and json looks like:  but the same dashbord imported by web ui is change and has such form:  ### What did you expect to happen? Dashboard import should work in the same way and not replace variable like ${DS_PROMETHEUS} to hardcoded datasource uid after import, so be optional. ### Did this work before? Yes in old days I believe.