The observed error was

    Failed to execute tcpdump on cilium-test-4/host-netns-8bpsl
    (kind-worker): command failed (pod=cilium-test-4/host-netns-8bpsl,
    container=): error reading from error stream: next reader: websocket:
    close 1005 (abnormal closure): unexpected EOF

The context here is that we are running `tcpdump` using a `cilium-cli`
initialized websocket executor, as provided by apimachinery. Websocket
for exec was made the default in Kubernetes 1.31, as SPDY is a protocol
which has been deprecated since 2015. We made it the default in Cilium
as users began to report seeing the following error when running Cilium
sysdump.

    error with exec request ... : Upgrade request required: ""

After making this change, we began to see CI flakes. These are most
likely due to a hardcoded 60 second timeout in the client-go websocket
exec implementation.

Working on this assumption, we can keep the websocket connection open by
doing the following:

1. Having `tcpdump` print to _both_ stdout, and the output file which we
   have been using for the sake of concurrency.
2. Waiting a short period of time before invoking `tcpdump`, as using
   the new invocation immediately upon opening the websocket connection
   resulted in the following error message on occasion during testing.

    command terminated with exit code 14

`tcpdump` exits with status 14 when it cannot write to one of its output
files. Since we have a relatively uncommon use case for the websocket
connection (the most common use of this websocket connection is the
`kubectl exec` command, which has used websocket by default since
Kubernetes 1.29), where we override all input and output files, we are
likely hitting a race with the websocket dialer for which we need to
wait for all of the `io.Writers` to be satisfied.

This commit makes both of the above changes.

fixes #37784

Signed-off-by: Andrew Sauber <andrew.sauber@isovalent.com>