fix(ci): purge unused dependencies

Jobs such as host image build fail as `docker-buildx-plugin` is
installed when attempting to install `docker-buildx`. As they share the
same path the task fails. Purging unused packages avoid this issue.

```
trying to overwrite '/usr/libexec/docker/cli-plugins/docker-buildx', which is also in package docker-buildx-plugin 0.29.1-1~ubuntu.22.04~jammy
```

Author: jackhodgkiss

.github/workflows/overcloud-host-image-build.yml

@@ -212,6 +212,15 @@ jobs:
           source src/kayobe-config/kayobe-env --environment ci-builder &&
           kayobe seed host configure -e seed_bootstrap_user=ubuntu --skip-tags network
 
+      - name: Remove unused dependencies
+        run: |
+          source venvs/kayobe/bin/activate &&
+          source src/kayobe-config/kayobe-env --environment ci-builder &&
+          kayobe seed host command run \
+          --command "sudo apt update && sudo apt autoremove --purge -y && sudo apt purge -y docker-buildx-plugin" --show-output
+        env:
+          KAYOBE_VAULT_PASSWORD: ${{ secrets.KAYOBE_VAULT_PASSWORD }}
+
       - name: Install dependencies
         run: |
           source venvs/kayobe/bin/activate &&