make unlock user aware

hetzner/autoinstall/tasks/unlock.yml

@@ -1,5 +1,6 @@
 - name: send unlock command
   raw: "printf '{{ autoinstall_disk_encryption_secret }}' | cryptroot-unlock"
+
 - name: wait for boot
   wait_for:
     delay: 5
@@ -8,3 +9,19 @@
     search_regex: OpenSSH|dropbear
     timeout: 300
   delegate_to: localhost
+
+- name: test ssh connection with {{ ansible_user }}
+  shell: |
+    ssh -p{{ ansible_ssh_port|default(22) }} \
+      -i {{ ansible_ssh_private_key_file }} \
+      -oStrictHostkeyChecking=no \
+      -oBatchMode=yes \
+      {{ ansible_user }}@{{ ansible_ssh_host }} echo test
+  register: connection_test
+  ignore_errors: yes
+  changed_when: False
+
+- name: set ansible_user
+  set_fact:
+      ansible_ssh_user: "{{ bootstrap_user|default('root') }}"
+  when: connection_test is succeeded