211: fix(modules/service/nixos-init): Use `boot.tmp.useTmpfs` option instead of `boot.tmpOnTmpfs` r=roberth a=MartinNikov
This change fixes the following warning:
```
trace: Obsolete option `boot.tmpOnTmpfs' is used. It was renamed to `boot.tmp.useTmpfs'.
```
This option was renamed in this PR:
https://github.com/NixOS/nixpkgs/pull/204534
Co-authored-by: MartinNikov <99672862+MartinNikov@users.noreply.github.com>
