refactor(k3s): streamline inventory and primary server IP handling

Signed-off-by: Tuan-Dat Tran <tuan-dat.tran@tudattr.dev>

roles/k3s_server/tasks/installation.yml

@@ -16,7 +16,7 @@
   ansible.builtin.command: |
     /tmp/k3s_install.sh server \
     --node-taint CriticalAddonsOnly=true:NoExecute \
-    --tls-san {{ k3s.loadbalancer.ip }}
+    --tls-san {{ hostvars['k3s-loadbalancer'].ansible_default_ipv4.address }}
   become: true
   async: 300
   poll: 0