Merge "floss: fix user name in rootless set up flow" into main

Then, we need to set up podman for [rootless

mode](https://docs.podman.io/en/latest/markdown/podman.1.html#rootless-mode):

```

sudo usermod --add-subuids 10000-75535 $USERNAME

sudo usermod --add-subgids 10000-75535 $USERNAME

sudo usermod --add-subuids 10000-75535 USERNAME

sudo usermod --add-subgids 10000-75535 USERNAME

```

## Container binary: setting up docker (alternative)