Eagerly create a milestone that is used in a feature spec
What does this MR do?
The milestone the test tries to set is lazily created so if its creation takes some time (e.g. on the CI), the test could fail because of that. I didn't manage to reproduce this locally, probably because the milestone is created quickly there, but this is definitely a problem on the CI.
The solution is to eagerly create the milestone since we need it in the example.
Closes #34609 (closed)