There's a closed pull request on the void-packages repository

grafana: Create /var/log/grafana on install
https://github.com/void-linux/void-packages/pull/26391

Description:
Directory is referenced in [`template`](https://github.com/Goorzhel/void-packages/blob/25102fb7685b04c1abf23456d3f78ce31c3094ce/srcpkgs/grafana/template#L49).

@the-maldridge