Mountpoint is not empty if docker containers were not quit

If colima is stopped while docker containers are running (e.g. `colima stop` or computer restart), mounting directories on the next start fails:
```
> msg="[hostagent] Mounting \"/Users/…/Library/Caches/colima\""
> msg="[hostagent] Mounting \"/Users/…/src\""
> msg="[hostagent] fuse: mountpoint is not empty"
> msg="[hostagent] fuse: if you are sure this is safe, use the 'nonempty' mount option"
```
When connecting to the instance via SSH an empty directory structure representing the docker mount points is found. After shutting down all running docker containers, stopping and starting colima the mount point works again.

Reproduce:
1. `colima start --mount ~/src:w`
2. `cd ~/src/foo/bar/prj/ && docker-compose up` with volumes, e.g. `volumes: - ./data/db:/var/lib/mysql:rw`
3. `colima stop && colima start`
4. See message `fuse: mountpoint is not empty`
5. `docker-compose down`
6. `colima ssh`, delete empty directory structure `…/src/foo/bar/prj/data/db` (via `sudo rm …`)
7. `colima stop && colima start`, mount works again

Looks like something is started before the files are mounted?