[DOCS] Remove "platinum" references for Docker TLS (#35890)

Author: Toby McLaughlin

docs/reference/security/securing-communications/configuring-tls-docker.asciidoc

@@ -66,7 +66,7 @@ version: '2.2'
 services:
   create_certs:
     container_name: create_certs
-    image: docker.elastic.co/elasticsearch/elasticsearch-platinum:{version}
+    image: {docker-image}
     command: >
       bash -c '
         if [[ ! -d config/certificates/certs ]]; then
@@ -103,7 +103,7 @@ version: '2.2'
 services:
   es01:
     container_name: es01
-    image: docker.elastic.co/elasticsearch/elasticsearch-platinum:{version}
+    image: {docker-image}
     environment:
       - node.name=es01
       - discovery.zen.minimum_master_nodes=2
@@ -128,7 +128,7 @@ services:
 
   es02:
     container_name: es02
-    image: docker.elastic.co/elasticsearch/elasticsearch:{version}
+    image: {docker-image}
     environment:
       - node.name=es02
       - discovery.zen.minimum_master_nodes=2
@@ -146,7 +146,7 @@ services:
     volumes: ['esdata_02:/usr/share/elasticsearch/data', './certs:$CERTS_DIR']
 
   wait_until_ready:
-    image: docker.elastic.co/elasticsearch/elasticsearch:{version}
+    image: {docker-image}
     command: /usr/bin/true
     depends_on: {"es01": {"condition": "service_healthy"}}