test(cluster): give the etcd timing tests' entrypoint harness the API port flag

The server argument builders now read api_port_flags, which the harness
did not set, so every one of its entrypoint tests failed on an unbound
variable.

Author: Mearman

tests/unit/test_cluster_etcd_timing.py

@@ -185,8 +185,10 @@ def server_args(self, builder: str, **env: str) -> list[str]:
                 'vpn_auth="name=tailscale,joinKey=example"',
                 'mesh_ip="100.64.0.1"',
                 function_source("set_etcd_timing_flags"),
+                function_source("set_api_port_flags"),
                 function_source(builder),
                 "set_etcd_timing_flags",
+                "set_api_port_flags",
                 f"{builder}",
                 'printf "%s\\n" "$server_args"',
             ]