Set `synapse_admin_container_network_deletion_enabled` to `false`

Signed-off-by: Suguru Hirahara <did🔑z6MkvVZk1A3KBApWJXv2Ju4H14ErDfRGxh8zxdXSZ4vACDg5>

group_vars/matrix_servers

@@ -5010,6 +5010,7 @@ synapse_admin_container_http_host_bind_port: "{{ (matrix_playbook_service_host_b
 synapse_admin_container_image_self_build: "{{ matrix_architecture not in ['arm64', 'amd64'] }}"
 
 synapse_admin_container_network: "{{ matrix_addons_container_network }}"
+synapse_admin_container_network_deletion_enabled: false
 
 synapse_admin_container_additional_networks: "{{ [matrix_playbook_reverse_proxyable_services_additional_network] if matrix_playbook_reverse_proxyable_services_additional_network else [] }}"