github: only publish latest release images

When building the container images for Packer (light and full), we
should only publish them in the version being built is a release, and
not a pre-release.

Changing this means that both light and full latest will always be only
a final release at any time.

.github/workflows/build.yml

@@ -242,10 +242,10 @@ jobs:
           target: release-light
           arch: ${{ matrix.arch }}
           tags: |
-            docker.io/hashicorp/${{ env.REPO_NAME }}:light
+            ${{ steps.get-product-version.output.prerelease-product-version == "" && format("docker.io/hashicorp/{0}:light", env.REPO_NAME) }}
             docker.io/hashicorp/${{ env.REPO_NAME }}:light-${{ env.version }}
             docker.io/hashicorp/${{ env.REPO_NAME }}:${{ env.version }}
-            public.ecr.aws/hashicorp/${{ env.REPO_NAME }}:light
+            ${{ steps.get-product-version.output.prerelease-product-version == "" && format("public.ecr.aws/hashicorp/{0}:light", env.REPO_NAME) }}
             public.ecr.aws/hashicorp/${{ env.REPO_NAME }}:light-${{ env.version }}
             public.ecr.aws/hashicorp/${{ env.REPO_NAME }}:${{ env.version }}
           dev_tags: |
@@ -272,9 +272,9 @@ jobs:
           target: release-full
           arch: ${{ matrix.arch }}
           tags: |
-            docker.io/hashicorp/${{ env.REPO_NAME }}:full
+            ${{ steps.get-product-version.output.prerelease-product-version == "" && format("docker.io/hashicorp/{0}:full", env.REPO_NAME) }}
             docker.io/hashicorp/${{ env.REPO_NAME }}:full-${{ env.version }}
-            public.ecr.aws/hashicorp/${{ env.REPO_NAME }}:full
+            ${{ steps.get-product-version.output.prerelease-product-version == "" && format("public.ecr.aws/hashicorp/{0}:full", env.REPO_NAME) }}
             public.ecr.aws/hashicorp/${{ env.REPO_NAME }}:full-${{ env.version }}
           dev_tags: |
             docker.io/hashicorppreview/${{ env.REPO_NAME }}:full-${{ env.version }}