Fix ID dependent jest spec

What does this MR do and why?

Fix ID dependent jest spec

This jest spec had a hard coded ID, but also relies on fixtures. Coincidentally one of the IDs in the fixtures ended up being the ID which was not supposed to exist in the fixture data.

We fix it by generating a unique ID which definitely does not exist in the fixture (sum of all IDs).

Screenshots or screen recordings

N/A

How to set up and validate locally

2. bundle exec rspec ee/spec/frontend/fixtures/analytics/devops_reports/devops_adoption/enabled_namespaces.rb
3. yarn run jest ee/spec/frontend/analytics/devops_reports/devops_adoption/components/devops_adoption_add_dropdown_spec.js

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.