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

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

roles/k3s_loadbalancer/tasks/installation.yml

@@ -0,0 +1,12 @@
+---
+- name: Update apt cache
+  ansible.builtin.apt:
+    update_cache: true
+  become: true
+
+- name: Install Nginx
+  ansible.builtin.apt:
+    name:
+      - nginx-full
+    state: present
+  become: true