Use native ARM builders for container builds (#1099)

This commit replaces #1088 and attempts to build a lading multi-platform
image by use of organization provided ARM native builders. Unsure if this'll
work but I figure it's worth a shot.

Signed-off-by: Brian L. Troutwine <[email protected]>

Author: blt

.github/actionlint.yml

@@ -0,0 +1,3 @@
+self-hosted-runner:
+  labels:
+    - arm-4core-linux-ubuntu24.04

.github/workflows/container.yml

@@ -8,8 +8,15 @@ env:
   IMAGE_NAME: ${{ github.repository }}
 
 jobs:
-  container:
-    runs-on: ubuntu-20.04
+  build:
+    runs-on: ${{ matrix.runner }}
+    strategy:
+      matrix:
+        include:
+          - arch: amd64
+            runner: ubuntu-20.04
+          - arch: arm64
+            runner: arm-4core-linux-ubuntu24.04
     permissions:
       contents: read
       packages: write
@@ -46,10 +53,42 @@ jobs:
         uses: docker/build-push-action@4f58ea79222b3b9dc2c8bbdd6debcef730109a75 # v6.9.0
         with:
           file: Dockerfile
-          builder: ${{ steps.buildx.outputs.name }}
+          tags: ${{ steps.meta.outputs.tags }}-${{ matrix.arch }}
           push: true
-          platforms: linux/amd64, linux/arm64
-          tags: ${{ steps.meta.outputs.tags }}
           labels: ${{ steps.meta.outputs.labels }}
-          cache-from: type=gha, scope=${{ github.workflow }}
-          cache-to: type=gha, scope=${{ github.workflow }}
+          cache-from: type=registry,ref=ghcr.io/datadog/lading:cache
+          cache-to: type=registry,ref=ghcr.io/datadog/lading:cache,mode=max
+
+  manifest:
+    name: Create Multi-Arch Manifest
+    needs: build
+    runs-on: ubuntu-20.04
+    permissions:
+      contents: read
+      packages: write
+
+    steps:
+      - name: Log in to Container Registry
+        uses: docker/login-action@9780b0c442fbb1117ed29e0efdff1e18412f7567 # v3.3.0
+        with:
+          registry: ${{ env.REGISTRY }}
+          username: ${{ github.actor }}
+          password: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@c47758b77c9736f4b2ef4073d4d51994fabfe349 # v3.7.1
+
+      - name: Extract Docker Metadata
+        uses: docker/metadata-action@8e5442c4ef9f78752691e2d8f8d19755c6f78e81 # v5.5.1
+        id: meta
+        with:
+          tags: |
+            type=sha,format=long
+          images: ${{ env.REGISTRY }}/${{ env.IMAGE_NAME }}
+
+      - name: Create and Push Multiarch Manifest
+        run: |
+          docker buildx imagetools create \
+            --tag ${{ steps.meta.outputs.tags }} \
+            ${{ steps.meta.outputs.tags }}-amd64 \
+            ${{ steps.meta.outputs.tags }}-arm64