[iris] Remove obsolete CoreWeave CI workflows and configs (#4197)

Delete the ephemeral smoke-cw workflow, dev-restart workflow, multihost
canary config and script, and smoke-cw cluster config. All replaced by
the always-on coreweave-ci cluster added in #4174. Rewrite
run_smoke_cw.sh
as a thin kubectl port-forward wrapper over pytest
tests/integration/iris/.

Deleted: iris-cloud-smoke-cw.yaml, iris-coreweave-dev-restart.yaml,
smoke-cw.yaml, coreweave-canary-multihost.yaml, coreweave_multihost.py.

Author: rjpower

.github/workflows/iris-cloud-smoke-cw.yaml

@@ -76,16 +76,16 @@ jobs:
           echo "${{ secrets.CW_KUBECONFIG }}" > ~/.kube/coreweave-iris
           chmod 600 ~/.kube/coreweave-iris
 
+      - name: Set up Docker Buildx
+        uses: docker/setup-buildx-action@v3
+
       - name: Log in to GitHub Container Registry
         uses: docker/login-action@v3
         with:
           registry: ghcr.io
           username: ${{ github.actor }}
           password: ${{ secrets.GITHUB_TOKEN }}
 
-      - name: Set up Docker Buildx
-        uses: docker/setup-buildx-action@v3
-
       # Delete stale worker pods so the autoscaler recreates them with fresh images.
       # Nodepools (and their underlying nodes) survive — this is the "warm start".
       - name: Reset worker pods