Post messages script - remove "sleep"
try to fix #2251

Also:
- remove the 1 second sleep after creating a discussion (not needed anymore). Maybe it was the source of the never finishing job
- add logs
- refactoring
- don't get all the discussions, only test if the bot has already created one (see https://github.com/huggingface/moon-landing/pull/8742 -> it's why we skip the tests for now)

Post messages script - remove "sleep": try to fix #2251

Also:
- remove the 1 second sleep after creating a discussion (not needed anymore). Maybe it was the source of the never finishing job
- add logs
- refactoring
- don't get all the discussions, only test if the bot has already created one (see https://github.com/huggingface/moon-landing/pull/8742 -> it's why we skip the tests for now)
