Refactor bootstrap-os (#10983)

* Remove leftover files for Coreos

Coreos was replaced by flatcar in 058438a25 but the file was copied
instead of moved.

* Remove workarounds for resolved ansible issues

* boostrap: Use first_found to include per distro

Using directly ID and VARIANT_ID with first_found allow for less manual
includes.
Distro "families" are simply handled by symlinks.

* boostrap: don't set ansible_python_interpreter

- Allows users to override the chosen python_interpreter with group_vars
  easily (group_vars have lesser precedence than facts)
- Allows us to use vars at the task scope to use a virtual env

Ansible python discovery has improved, so those workarounds should not
be necessary anymore.
Special workaround for Flatcar, due to upstream ansible not willing to
support it.

roles/bootstrap-os/tasks/flatcar.yml

@@ -0,0 +1,34 @@
+---
+# Flatcar Container Linux ships without Python installed
+
+- name: Check if bootstrap is needed
+  raw: stat /opt/bin/.bootstrapped
+  register: need_bootstrap
+  failed_when: false
+  changed_when: false
+  tags:
+    - facts
+
+- name: Run bootstrap.sh
+  script: bootstrap.sh
+  become: true
+  environment: "{{ proxy_env }}"
+  when:
+    - need_bootstrap.rc != 0
+
+# Workaround ansible https://github.com/ansible/ansible/pull/82821
+# We set the interpreter rather than ansible_python_interpreter to allow
+# - using virtual env with task level ansible_python_interpreter later
+# - let users specify an ansible_python_interpreter in group_vars
+
+- name: Make interpreter discovery works on Flatcar
+  set_fact:
+    ansible_interpreter_python_fallback: "{{ ansible_interpreter_python_fallback + [ '/opt/bin/python' ] }}"
+
+- name: Disable auto-upgrade
+  systemd:
+    name: locksmithd.service
+    masked: true
+    state: stopped
+  when:
+    - coreos_locksmithd_disable