Fix board milestone spec
What does this MR do?
Fixes the failing rspec 19 20 spec as found in https://gitlab.com/gitlab-org/gitlab-ee/builds/15462262
Are there points in the code the reviewer needs to double check?
Shouldn't be
Why was this MR needed?
Fixes failed build
Screenshots (if relevant)
None
Does this MR meet the acceptance criteria?
Yes