Migration: reduce the number of rows prefetched by pgloader

[kemenaran]

This helps fixing stack overflow errors on large databases.

See https://forum.yunohost.org/t/need-testers-for-the-latest-mattermost-upgrade/23992/29?u=kemenaran

[kemenaran]

!testme

[yunohost-bot]

:carousel_horse:

[kemenaran]

Mmm, there's an

229250 DEBUG {"timestamp":"2023-04-03 12:20:00.009 Z","level":"error","msg":"Failed to get system bot","caller":"app/post.go:2009","error":"GetSystemBot: List of admins is empty."}

I don't know what to do with this.

Let's try the test run again…

[kemenaran]

!testme

[yunohost-bot]

May the CI gods be with you!