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

site.yml

@@ -85,5 +85,5 @@
         dest: ./kubeconfig
         flat: true
       when: >-
-        ansible_facts.hostname == hostvars[groups[group_name_master | default('master')][0]]
-        ['ansible_facts']['hostname']
+        ansible_facts.hostname ==
+        hostvars[groups[group_name_master | default('master')][0]]['ansible_facts']['hostname']