fix(k3s_server): skip k3s-init log collection when the destination is unset (#721)

* fix(k3s_server): skip k3s-init log collection when the destination is unset

The guard on the k3s-init diagnostics include used a boolean default for
the ANSIBLE_K3S_LOG_DIR lookup so that the when conditional would be a real
boolean. That is unnecessary: `log_destination | default('') != ''` is a
comparison and always evaluates to a bool, so ansible-core 2.19 never sees
a non-boolean conditional here.

The boolean default also defeats the guard. With ANSIBLE_K3S_LOG_DIR unset,
log_destination is the bool False, and `False != ''` is True in Python
because False == 0. The include therefore runs on every provisioning run,
executing the journalctl, systemctl, ip, ss, iptables, service_facts, ping
and wait_for diagnostics in fetch_k3s_init_logs.yml, then creating a
directory literally named "False" in the operator's working directory.

Use an empty-string default so the unset case renders "" and the guard
skips. CI did not catch this because .github/workflows/test.yml always
exports ANSIBLE_K3S_LOG_DIR.

Add a regression test that parses the role, renders the real log_destination
expression for both the unset and set cases, and asserts that no boolean
default has been reintroduced.

* chore(site): wrap the over-long kubeconfig fetch conditional

roles/k3s_server/tasks/main.yml

@@ -124,13 +124,18 @@
   always:
     - name: Save logs of k3s-init.service
       ansible.builtin.include_tasks: fetch_k3s_init_logs.yml
-      # ANSIBLE_K3S_LOG_DIR is a path string when set; evaluate it as a boolean
-      # so the conditional is a real boolean (ansible-core 2.19 rejects string
-      # conditionals derived from env vars).
+      # The env lookup default must be an empty string, not the boolean
+      # False. The `!= ''` comparison below always evaluates to a bool, so
+      # ansible-core 2.19 never sees a non-boolean conditional and no boolean
+      # default is needed. With a boolean default, an unset ANSIBLE_K3S_LOG_DIR
+      # leaves log_destination as the bool False, and `False != ''` is True
+      # because False == 0. The guard would then always pass, running the
+      # diagnostics on every provisioning run and creating a directory
+      # literally named 'False' in the operator's working directory.
       when: log_destination | default('') != ''
       vars:
         log_destination: >-
-          {{ lookup('ansible.builtin.env', 'ANSIBLE_K3S_LOG_DIR', default=False) }}
+          {{ lookup('ansible.builtin.env', 'ANSIBLE_K3S_LOG_DIR', default='') }}
     - name: Kill the temporary service used for initialization
       ansible.builtin.systemd:
         name: k3s-init