Investigate net::ERR_TIMED_OUT for Reference Creation step

[MathieuLamiot]

Context
https://wp-media.slack.com/archives/C05NH7JU4S2/p1717624318609909

Sometimes, the Reference Creation steps throws timeouts as seen on the thread. Usually, it is associated with bad internet connection. However, the pages look like they are well open.

Expected beavhior

• Investigate and understand the issue. Maybe fix it.

Additional information
Puppeteer throws a timeout usually when the "completion" condition is not met. Available conditions are:

load - navigation is finished when the load event is fired.
domcontentloaded - navigation is finished when the DOMContentLoaded event is fired.
networkidle0 - navigation is finished when there are no more than 0 network connections for at least 500 ms.
networkidle2 - navigation is finished when there are no more than 2 network connections for at least 500 ms.

Maybe sometimes, there is one resource that takes a very long time to load (or can't be loaded)? This could be seen in the network tab of dev tools for instance.
It could be configured in BackstopJS: garris/BackstopJS#1123 (comment)