This MR is a collection of smaller unrelated fixes & improvements for system tests.
The MR also attempts to improve CI stability by allowing re-runs of selected system tests which are known for their high false positive rate. Following tests were allowed to be re-run in case of failure:
I also considered allowing re-runs for these tests, but decided against it for now:
statschannel - seems to be isolated to FreeBSD as of late, related #1621 (closed)
fetchlimit - not really sure what's going on there, but it might be a candidate upon further investigation, related #3535 (closed)
autosign - the cause seems to be randomness, but it hasn't been popping up that often #1565