fix(ci): join control planes to the runner network

scripts/docker_host_address.py

@@ -1,39 +0,0 @@
-#!/usr/bin/env python3
-"""Print the Docker host address seen by a socket-shared Linux CI container."""
-
-from __future__ import annotations
-
-import socket
-import struct
-import sys
-from pathlib import Path
-
-
-def default_ipv4_gateway(route_table: str) -> str:
-    """Return the active default gateway from Linux ``/proc/net/route``."""
-
-    for line in route_table.splitlines()[1:]:
-        fields = line.split()
-        if len(fields) < 4 or fields[1] != "00000000":
-            continue
-        try:
-            gateway = int(fields[2], 16)
-            flags = int(fields[3], 16)
-        except ValueError:
-            continue
-        if flags & 0x2:  # RTF_GATEWAY
-            return socket.inet_ntoa(struct.pack("<I", gateway))
-    raise ValueError("no active IPv4 default gateway in /proc/net/route")
-
-
-def main() -> int:
-    try:
-        print(default_ipv4_gateway(Path("/proc/net/route").read_text(encoding="utf-8")))
-    except (OSError, ValueError) as exc:
-        print(f"docker-host-address: {exc}", file=sys.stderr)
-        return 1
-    return 0
-
-
-if __name__ == "__main__":
-    raise SystemExit(main())