ci: pre download docker images used in bats tests (#3452)

Should help with issues such as https://github.com/project-zot/zot/actions/runs/18457240003/job/52580780359

Signed-off-by: Andrei Aaron <andreifdaaron@gmail.com>

test/blackbox/ci.sh

@@ -7,6 +7,10 @@ SCRIPTPATH="$( cd -- "$(dirname "$0")" >/dev/null 2>&1 ; pwd -P )"
 BATS=${SCRIPTPATH}/../../hack/tools/bin/bats
 PATH=$PATH:${SCRIPTPATH}/../../hack/tools/bin
 
+# Pre-download Docker images before running tests
+echo "Setting up Docker images..."
+${SCRIPTPATH}/setup_images.sh
+
 tests=("pushpull" "pushpull_authn" "delete_images" "referrers" "metadata" "anonymous_policy"
       "annotations" "detect_manifest_collision" "cve" "sync" "sync_docker" "sync_replica_cluster"
       "scrub" "garbage_collect" "metrics" "metrics_minimal" "multiarch_index" "docker_compat" "redis_local" "redis_session_store"

test/blackbox/setup_images.sh

@@ -0,0 +1,41 @@
+#!/bin/bash
+
+# Pre-download Docker images used in blackbox tests
+# This script ensures all required images are available before tests start
+
+set -e
+
+echo "Pre-downloading Docker images for blackbox tests..."
+
+# List of images used in the tests
+IMAGES=(
+    "nats:2.11.1"
+    "natsio/nats-box:latest"
+    "python:3"
+    "redis:latest"
+)
+
+# Function to download an image if not already present
+download_image() {
+    local image="$1"
+    echo "Checking for image: $image"
+    
+    if docker image inspect "$image" >/dev/null 2>&1; then
+        echo "✓ Image $image already exists"
+    else
+        echo "Downloading image: $image"
+        if docker pull "$image"; then
+            echo "✓ Successfully downloaded $image"
+        else
+            echo "✗ Failed to download $image"
+            return 1
+        fi
+    fi
+}
+
+# Download all images
+for image in "${IMAGES[@]}"; do
+    download_image "$image"
+done
+
+echo "All Docker images are ready for testing!"