Platform updates keep using the proven preparation path

A new, much faster way of preparing content types during a platform update was introduced earlier today. Its first run against a large production mesh read only part of the available source content, and reported many healthy types as broken. Nothing was lost and no page changed — the update safety-check spotted it and kept the previous version serving — but the fast path is not trustworthy yet.

Updates now use the proven preparation path by default, and the faster one has to be switched on deliberately. The speed improvements that did hold up — no more artificial pauses between types during an update — remain in place.