agent: fix container ci

Author: ayuskauskas

.github/workflows/build_agent_container.yaml

@@ -48,11 +48,13 @@ jobs:
       - name: Set up Docker Buildx
         uses: docker/setup-buildx-action@v3
 
-      - name: Check outputs
-        run: cd agent && make docker-build-only
+      - name: Build the agent container image
+        run: |
+          cd agent
+          REGISTRY=${REGISTRY@L} make docker-build-only
         env:
           AGENT_IMAGE: ${{env.IMAGE_NAME}}/agent 
-          TAGS: -t ${{ env.REGISTRY }}/${{env.IMAGE_NAME}}/agent:${{ github.sha }}
+          TAGS: -t ${{ env.REGISTRY@L }}/${{env.IMAGE_NAME}}/agent:${{ github.sha }}
 
       # This step generates an artifact attestation for the image, which is an unforgeable statement about where and how it was built. It increases supply chain security for people who consume the image. For more information, see [AUTOTITLE](/actions/security-guides/using-artifact-attestations-to-establish-provenance-for-builds). 
       - name: Generate artifact attestation