Fix erp5 slow queries logs
ERP5 software release has some support for mariadb slow queries:
- run
pt-query-digest
daily - check that the number of slow queries and the slowest slow query do not exceed some thresholds defined as instance parameters
but this had issues:
- the daily
pt-query-digest
reports where kept as not-compressed text files, which over time takes quite a lot of disk space - the threshold detection was not working, since strings and floats were compared - see slapos.toolbox!83 (merged)
This uses new techniques in software release testing from slapos.core!245 (merged), we use faketime to simulate running crontabs and promises at a specific time in the future, so that we can assert the exact expected behaviour of crontab scripts.