Change TCP keepalive defaults

[flobernd]

Based on a request by @DaveCTurner, clients should use consistent TCP keepalive defaults. See related issue for more details and reasoning to not follow the old RFC 9293.

The following defaults should be set:

• TCP_KEEPIDLE = 300 s
• TCP_KEEPINTVL = 1 s
• TCP_KEEPCNT = 5

Related to https://github.com/elastic/devtools-team/issues/857

Microsoft itselfs recommends to lower the global defaults for e.g. Windows Server:
https://learn.microsoft.com/en-us/previous-versions/windows/it-pro/windows-server-2008-R2-and-2008/dd349797(v=ws.10)?redirectedfrom=MSDN

TCP_KEEPIDLE = KeepAliveTime
TCP_KEEPCNT = TcpMaxDataRetransmissions