Fix conformance release workflow (#1198)

Problem: The job used in the conformance tests to wait for the release to exist wasn't working properly. It only saw jobs in progress, and not jobs that are pending, which is what we needed to wait for.

Solution: Removed the action and replaced with a basic polling loop to ensure the NGF images exist before continuing with the tests.

.github/workflows/conformance.yml

@@ -14,6 +14,10 @@ on:
   schedule:
     - cron: "0 4 * * *" # run every day at 4am UTC
 
+defaults:
+  run:
+    shell: bash
+
 concurrency:
   group: ${{ github.ref_name }}-conformance
   cancel-in-progress: true
@@ -134,19 +138,16 @@ jobs:
 
       - name: Wait for release to exist
         if: startsWith(github.ref, 'refs/tags/')
-        uses: lewagon/wait-on-check-action@e106e5c43e8ca1edea6383a39a01c5ca495fd812 # v1.3.1
-        with:
-          ref: ${{ github.ref }}
-          check-name: 'Build Image'
-          repo-token: ${{ secrets.GITHUB_TOKEN }}
+        run: |
+          REF=${{ github.ref_name }}
+          until docker pull ghcr.io/nginxinc/nginx-gateway-fabric:${REF#v}; do sleep 5; done
+          until docker pull ghcr.io/nginxinc/nginx-gateway-fabric/nginx:${REF#v}; do sleep 5; done
 
       - name: Setup conformance tests
         run: |
           ngf_prefix=$(echo ${{ steps.ngf-meta.outputs.tags }} | cut -d ":" -f 1)
           ngf_tag=$(echo ${{ steps.ngf-meta.outputs.tags }} | cut -d ":" -f 2)
-          if [ ${{ github.event_name }} == "schedule" ]; then
-          export GW_API_VERSION=main
-          fi
+          if [ ${{ github.event_name }} == "schedule" ]; then export GW_API_VERSION=main; fi
           make install-ngf-local-no-build NGF_PREFIX=${ngf_prefix} NGF_TAG=${ngf_tag}
         working-directory: ./conformance