Refactor creating GCP disks (#8330)

.github/workflows/sub-deploy-integration-tests-gcp.yml

@@ -194,11 +194,9 @@ jobs:
           PREFER_MAIN_CACHED_STATE: ${{ inputs.prefer_main_cached_state }}
         run: |
           source ./.github/workflows/scripts/gcp-get-cached-disks.sh
-          echo "cached_disk_name=${CACHED_DISK_NAME}" >> "${GITHUB_OUTPUT}"
           echo "STATE_VERSION=${LOCAL_STATE_VERSION}" >> "${GITHUB_ENV}"
           echo "CACHED_DISK_NAME=${CACHED_DISK_NAME}" >> "${GITHUB_ENV}"
-          echo "DISK_OPTION=image=$CACHED_DISK_NAME," >> "${GITHUB_ENV}"
-
+          echo "cached_disk_name=${CACHED_DISK_NAME}" >> "${GITHUB_OUTPUT}"
 
       # Create a Compute Engine virtual machine and attach a cached state disk using the
       # $CACHED_DISK_NAME variable as the source image to populate the disk cached state
@@ -207,12 +205,17 @@ jobs:
         id: create-instance
         shell: /usr/bin/bash -x {0}
         run: |
+          NAME="${{ inputs.test_id }}-${{ env.GITHUB_SHA_SHORT }}"
+          DISK_PARAMS="size=400GB,type=pd-ssd,name=${NAME},device-name=${NAME}"
+          if [ -n "${{ env.CACHED_DISK_NAME }}" ]; then
+            DISK_PARAMS+=",image=${{ env.CACHED_DISK_NAME }}"
+          fi
           gcloud compute instances create-with-container "${{ inputs.test_id }}-${{ env.GITHUB_REF_SLUG_URL }}-${{ env.GITHUB_SHA_SHORT }}" \
           --boot-disk-size 50GB \
           --boot-disk-type pd-ssd \
           --image-project=cos-cloud \
           --image-family=cos-stable \
-          --create-disk=${DISK_OPTION}name="${{ inputs.test_id }}-${{ env.GITHUB_SHA_SHORT }}",device-name="${{ inputs.test_id }}-${{ env.GITHUB_SHA_SHORT }}",size=400GB,type=pd-ssd \
+          --create-disk="${DISK_PARAMS}" \
           --container-image=gcr.io/google-containers/busybox \
           --machine-type ${{ vars.GCP_LARGE_MACHINE }} \
           --network-interface=subnet=${{ vars.GCP_SUBNETWORK }} \