Remove stable-specific image (#700)

This was only introduced as a temporary solution for Discourse 2.8, which is now EOL

launcher

@@ -93,7 +93,6 @@ config_file=containers/"$config".yml
 cidbootstrap=cids/"$config"_bootstrap.cid
 local_discourse=local_discourse
 image="discourse/base:2.0.20230313-1023"
-image_stable="discourse/base:2.0.20230222-0048"
 docker_path=`which docker.io 2> /dev/null || which docker`
 git_path=`which git`
 
@@ -236,14 +235,6 @@ check_prereqs() {
     pull_image
   fi
 
-  # use an older image for stable
-  version=$(cat $config_file | $docker_path run $user_args --rm -i -a stdout -a stdin $image ruby -e \
-      "require 'yaml'; puts YAML.load(STDIN.readlines.join)['params']['version']")
-  if [ "$version" = "stable" ]; then
-    image=$image_stable
-    pull_image
-  fi
-
   # 5. running recommended git version
   test=($($git_path --version))  # Get git version string
   test=${test[2]//,/}  # Get version alone and strip comma if exists