Add a cop for no capitalization on expectations [RUN AS-IF-FOSS]

What does this MR do?

• Upgrades gitlab-styles to 5.2.0
• Applies new cop from that version bump to enforce capitalization and strip leading/trailing spaces.
  • styleguide vote process performed during https://gitlab.com/gitlab-org/gitlab-styles/-/merge_requests/59

What doesn't this MR do?

• Concern itself with proper grammar on any of the items changed (merely ran rubocop -a --only RSpec/ExampleStartingCharacter)
• Concern itself with " vs '

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

Related to #280840