fix synapse-admin image prefix

roles/custom/matrix-synapse-admin/defaults/main.yml

@@ -16,7 +16,7 @@ matrix_synapse_admin_container_image_self_build_repo: "https://github.com/etkecc
 # renovate: datasource=docker depName=ghcr.io/etkecc/synapse-admin
 matrix_synapse_admin_version: v0.10.3-etke12
 matrix_synapse_admin_docker_image: "{{ matrix_synapse_admin_docker_image_name_prefix }}etkecc/synapse-admin:{{ matrix_synapse_admin_version }}"
-matrix_synapse_admin_docker_image_name_prefix: "{{ 'localhost/' if matrix_synapse_admin_container_image_self_build else matrix_container_global_registry_prefix }}"
+matrix_synapse_admin_docker_image_name_prefix: "{{ 'localhost/' if matrix_synapse_admin_container_image_self_build else 'ghcr.io/ }}"
 matrix_synapse_admin_docker_image_force_pull: "{{ matrix_synapse_admin_docker_image.endswith(':latest') }}"
 
 # The base container network