ci: use arch-scoped buildkit service (buildkit-<arch>) instead of per-instance

.woodpecker/container.yaml

@@ -42,13 +42,13 @@ steps:
         from_secret: registry_token
       # In-cluster native arm64 buildkit (kotkan's arch). ci/local.sh treats
       # this as a native remote builder and skips qemu emulation.
-      BUILDKIT_ADDR: "tcp://buildkit-rootless-arm64.infra.svc.cluster.local:1234"
+      BUILDKIT_ADDR: "tcp://buildkit-arm64.infra.svc.cluster.local:1234"
       PUBLISH: "1"
     commands:
       - echo "▸ arch=$(uname -m)"
       # Wait for the in-cluster buildkit to be reachable (it can be cold).
       - |
-        BUILDER_HOST="buildkit-rootless-arm64.infra.svc.cluster.local"
+        BUILDER_HOST="buildkit-arm64.infra.svc.cluster.local"
         BUILDER_PORT="1234"
         echo "Waiting for buildkit at $BUILDER_HOST:$BUILDER_PORT..."
         for i in $(seq 1 30); do

ci/local.sh

@@ -16,7 +16,7 @@
 # Builder is parameterized:
 #   BUILDKIT_ADDR  default docker-container://local  (dev: local buildkitd)
 #                  CI overrides to the in-cluster native-arch remote, e.g.
-#                  tcp://buildkit-rootless-arm64.infra.svc.cluster.local:1234
+#                  tcp://buildkit-arm64.infra.svc.cluster.local:1234
 #
 # kotkan (the deploy target) is arm64, so the default target arch is arm64.
 # Foreign-arch (an arch != the host) is emulated via qemu binfmt and is