Unified role execution across multiple hosts (#18)

This refactoring is a strategic move towards ensuring our Ansible playbooks are DRY (Don't Repeat Yourself) and adhering to the best practices for efficient Ansible use. It contributes significantly to the overall manageability of our automation tasks and facilitates easier future updates.
diff --git a/ansible/playbooks/install-skywalking.yml b/ansible/playbooks/install-skywalking.yml
index 1720cb2..b7e3902 100644
--- a/ansible/playbooks/install-skywalking.yml
+++ b/ansible/playbooks/install-skywalking.yml
@@ -30,14 +30,8 @@
   roles:
     - install-java
 
-- name: Download and configure Apache SkyWalking APM OAP Service
-  hosts: skywalking_oap
-  gather_facts: false
-  roles:
-    - skywalking
-
-- name: Download and configure Apache SkyWalking APM UI Service
-  hosts: skywalking_ui
+- name: Download and configure Apache SkyWalking APM Service on all hosts
+  hosts: all
   gather_facts: false
   roles:
     - skywalking