3.17 - SaaS visits generate LRC entries in DB but without hashes

[MathieuLamiot]

Context To be done after #6909

https://wp-media.slack.com/archives/CUT7FLHF1/p1724319751032379?thread_ts=1724257215.870589&cid=CUT7FLHF1 When triggering a SaaS warmup of Performance Hints (clear the LRC & ATF tables, and trigger a warmup by changing permalinks for example, or clicking the button to clear perf. hints), after a while, LRC table is populated but all entries have no hashes.

See the first investigation below: there is one issue that prevents the SaaS visits from working at all, and then probably a 2nd issue that make the feature inconsistent. Consider working on Issue n°1 first, and then circling back to identify the issue n°2 to do it step by step.

This GH issue is to cover issue n°2 (inconsistency), once issue n°1 is fixed (in #6909)

Expected behavior SaaS visits should consistently produce the same results in the DB as a manual visit with a similar viewport size.

Acceptance Criteria Trigger a Performance Hints warmup. After a while, LRC table must be filled with entries that have the same hashes as a manual visit on this page. Repeat 10 times.

Additional information See the thread. @mostafa-hisham can help for the SaaS side investigation.