Python: remove unconditional sleep on spawn

[teh-cmc]

Removes the unconditional sleep(0.5) on the spawn path in python, improving latency.

This mimics what happens in the new Rust/C/C++ spawn APIs:

rerun/crates/re_sdk/src/recording_stream.rs

Lines 1309 to 1321 in 3f41c3b

	crate::spawn(opts)?;
	// Give the newly spawned Rerun Viewer some time to bind.
	//
	// NOTE: The timeout only covers the TCP handshake: if no process is bound to that address
	// at all, the connection will fail immediately, irrelevant of the timeout configuration.
	// For that reason we use an extra loop.
	for _ in 0..5 {
	if TcpStream::connect_timeout(&connect_addr, Duration::from_secs(1)).is_ok() {
	break;
	}
	std::thread::sleep(Duration::from_millis(100));
	}

What

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• I have read and agree to Contributor Guide and the Code of Conduct
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• I have tested demo.rerun.io (if applicable)
• The PR title and labels are set such as to maximize their usefulness for the next release's CHANGELOG

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[jleibs]

Ahh nice, should have realized this opportunity when I added the check.