fix(test): add sleep to wait for socat spinup in test_tap_offload

We are seeing an intermittent failure of the form

FAILED
integration_tests/functional/test_net.py::test_tap_offload[uvm_restored-vmlinux-5.10.236]
- ChildProcessError:
[17861] Command:
['ip', 'netns', 'exec', 'netns-gw1-1', 'ssh', '-o',
'ControlPath=/srv/jailer/firecracker/4b087ca9-b1ec-4bf8-9dfd-2d6dcc378b9e/root/ssh-0.sock',
'[email protected]', 'sync; cat /tmp/out.txt']
[17861] stdout:
[17861] stderr:
cat: /tmp/out.txt: No such file or directory

We theorize this is due to not waiting long enough for socat to spin up,
so add a quick sleep.

Signed-off-by: Patrick Roy <[email protected]>

Author: roypat

tests/integration_tests/functional/test_net.py

@@ -111,6 +111,9 @@ def test_tap_offload(uvm_any):
         f"nohup socat UDP4-LISTEN:{port} OPEN:{out_filename},creat > /dev/null 2>&1 &"
     )
 
+    # wait for socat server to spin up
+    time.sleep(1)
+
     # Try to send a UDP message from host with UDP offload enabled
     vm.netns.check_output(f"python3 ./host_tools/udp_offload.py {vm.ssh.host} {port}")