Clean up pytest files in /tmp after test runs

[jvperrin]

Currently, tests (using pytest) can leave files around in /tmp (~ 800 MiB per pytest directory) which can then lead to /tmp completely running out of space since it is only 4 GiB in total:

jvperrin@supernova:~$ sudo du -sh /tmp/* | sort -h | tail -n 2
872M	/tmp/pytest-of-gleeb
2.6G	/tmp/pytest-of-dkessler

This has happened several times before, but we should have a better solution than just temporarily cleaning out space again (for instance running a rm of the relevant directory in the Makefile after running tests, or running tmpreaper on these directories periodically).

Additionally, increasing the size of /tmp on supernova would help, but given the size of these pytest outputs (~ 800 MiB per directory), that wouldn't help that much.

[BernardZhao]

Any hints as where to look to start fixing this? I tried running make-test myself a few times, and then looking in tmp for pytest-of-bernardzhao, only to find that it was full of empty directories. I am wondering what kind of strange situations could have caused the tmp to grow so big, and if they are even strictly related with only ocfweb.