Make matrix-livekit-jwt-service role not reference foreign variables (except the matrix-base ones)

roles/custom/matrix-livekit-server/tasks/install.yml

@@ -56,7 +56,7 @@
         dest: "{{ livekit_server_container_src_files_path }}"
         force: "yes"
       become: true
-      become_user: "{{ matrix_user_username }}"
+      become_user: "{{ livekit_server_uid }}"
       register: livekit_server_git_pull_results
 
     - name: Ensure LiveKit Server container image is built