Only capture eventlogs on nightly run

Fixes ghc#21734 (closed)

Uses new var EVENTLOGGING (see ghc!8468 (closed))

assigned to @chreekat

changed the description

resolved all threads

added 2 commits

• 00774737 - Always create eventlogs dir
• 23b680d2 - Guard eventlog processing with its own env var

Compare with previous version

enabled an automatic merge when the pipeline for 23b680d2 succeeds

changed the description

Running with job with EVENTLOGGING=1 just to test that path: https://gitlab.haskell.org/ghc/head.hackage/-/jobs/1084122

Meh, that's a waste of time, I tested it locally. What really matters is seeing the whole thing go through. This passed on 9.2 and failed for unrelated reasons on master, so I'm going to go ahead and merge.

canceled the automatic merge

merged