[debian-mysql] Bug#1059904: mariadb autopkgtest "upstream" is flaky, time sink

[Otto Kekäläinen]

## arm64

All green at https://ci.debian.net/packages/m/mariadb/testing/arm64/
Latest log has "Completed: All 1049 tests were successful."

## i386

Likewise, all green at https://ci.debian.net/packages/m/mariadb/testing/i386/
Latest log has "Completed: All 1047 tests were successful.".

## armel

Flaky at https://ci.debian.net/packages/m/mariadb/testing/armel/
Last passing a couple days ago: Completed: All 1047 tests were successful.
All failing ones on main.subselect* for which I have a bugfix.

## armhf

Flaky at https://ci.debian.net/packages/m/mariadb/testing/armhf/
Latest passed: Completed: All 1046 tests were successful.
Likewise to armel, failures on main.subselect*

## s390x

Flaky at https://ci.debian.net/packages/m/mariadb/testing/s390x/
Last passed a couple days ago: All 1047 tests were successful.
Likewise to armel, failures on main.subselect*

## amd64

Finally, amd64 flaky at https://ci.debian.net/packages/m/mariadb/testing/amd64/
Last passed a couple days ago: Completed: All 1049 tests were successful.

All failures on subselect as well, which is an upstream regression in
10.11.6: https://jira.mariadb.org/browse/MDEV-32843
Fix is pending on
https://salsa.debian.org/otto/mariadb-server/-/commits/dev-otto but
still need to finalize a bit before upload.


Summary: the number of tests is not flaky on passed runs. The number
of attempted test runs is fluctuating only when failures happend and
tests re-run.