speedup cache warmup if cache exists

Author: pk910

.github/workflows/_shared-prepare-docker-cache.yaml

@@ -23,20 +23,29 @@ jobs:
         echo "kurtosis_version=$kurtosis_version" >> $GITHUB_OUTPUT
 
         echo "Kurtosis version: $kurtosis_version"
+    - name: Check if cache key exists
+      id: check_cache
+      uses: actions/cache@v4
+      with:
+        key: "kurtosis-docker-${{ runner.os }}-${{ steps.kurtosis_version.outputs.kurtosis_version }}"
+        path: .
+        lookup-only: true
+
     - name: Cache Docker images.
-      id: cache
+      if: ${{ !steps.check_cache.outputs.cache-hit }}
       uses: ScribeMD/docker-cache@0.5.0
       with:
-        key: kurtosis-docker-${{ runner.os }}-${{ steps.kurtosis_version.outputs.kurtosis_version }}
+        key: "kurtosis-docker-${{ runner.os }}-${{ steps.kurtosis_version.outputs.kurtosis_version }}"
 
     - name: "Generate dummy kurtosis config"
+      if: ${{ !steps.check_cache.outputs.cache-hit }}
       shell: bash
       run: |
         mkdir -p ./temp
         echo "{\"participants\": []}" > ./temp/test-network.yaml
 
     - name: Run kurtosis testnet for cache warmup
-      if: ${{ steps.cache.outputs.cache-hit == 'false' }}
+      if: ${{ !steps.check_cache.outputs.cache-hit }}
       continue-on-error: true
       id: testnet
       uses: ethpandaops/kurtosis-assertoor-github-action@v1