fix(fetch): honor server Keep-Alive timeout hint in APIRequestContext

[Mohan Ram (mohanram-dev)]

Fixes #42698

Description

When a server returns a Keep-Alive: timeout=N response header, Node.js (lib/_http_agent.js keepSocketAlive()) evaluates:

let agentTimeout = this.options.timeout || 0;
if (hint) {
  let serverHintTimeout = (NumberParseInt(hint) * 1000) - this.agentKeepAliveTimeoutBuffer;
  serverHintTimeout = serverHintTimeout > 0 ? serverHintTimeout : 0;
  if (serverHintTimeout === 0) {
    canKeepSocketAlive = false;
  } else if (serverHintTimeout < agentTimeout) {
    agentTimeout = serverHintTimeout;
  }
}

[Mohan Ram (mohanram-dev)]

@microsoft-github-policy-service agree