Remove check_images

Removed check_images due to removal of -t parameter and $images being set in docker-bench-security.sh

Signed-off-by: Niall T <jammasterj89@gmail.com>

tests/4_container_images.sh

@@ -1,22 +1,5 @@
 #!/bin/sh
 
-check_images() {
-if [ -n "$imgList" ]; then
-    pattern=$(echo "$imgList" | sed 's/,/ /g')
-    for img in $pattern; do
-      echo "Looking for image $img"
-      sha256=$(docker images | grep $img | awk '{print $3}')
-      if [ -z "$sha256" ]; then
-        echo "Image $img not found. Exiting."
-        exit 1
-      fi
-      images="$sha256"
-      echo "images ------------------------------------ " $images
-      echo "sha356" $sha256
-    done
-fi
-}
-
 check_4() {
   logit "\n"
   id_4="4"