Improve runtime of usage data core specs

What does this MR do?

Improve runtime of usage data core specs and also refactor with subject to make some spec more concise

Issue #241260 (closed)

Before

$ bundle exec rspec -fd spec/lib/gitlab/usage_data_spec.rb
Finished in 2 minutes 51.1 seconds (files took 24.09 seconds to load)
65 examples, 0 failures

After moving hash key checks to one example

Finished in 2 minutes 34.3 seconds (files took 22.99 seconds to load)

Queries saved: 5850

Screenshots

• List of slow tests https://gitlab-org.gitlab.io/rspec_profiling_stats/

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Documentation (if required)
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content

Availability and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers
• Informed Infrastructure department of a default or new setting change, if applicable per definition of done

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team