Update okr_spec.rb to reload data before assertion

What does this MR do and why?

Resolves flaky test reported in Flaky test ee/spec/features/projects/work_items... (#412787 - closed)

Due to my GDK is going through Ruby and Postgres upgrade right now, I cannot verify locally any time soon, so will rely on the feedback from CI.

MR acceptance checklist

This checklist encourages us to confirm any changes have been analyzed to reduce risks in quality, performance, reliability, security, and maintainability.

• I have evaluated the MR acceptance checklist for this MR.