Refactor spec/unit/utils_spec.rb

What does this MR do?

This patch refactors the utils_spec.rb test suite , primarily focusing on the String class extensions such as #number?, #unquote, and #chars_only. The refactor introduces a more structured and DRY approach by utilizing a table-driven tests, each defined by an input and an expected output, for both the #number? and #unquote methods.

What are the relevant issue numbers?

Refactor semver_dialects tests (gitlab-org/gitlab#441450 - closed) • Philip Cunningham • 16.10

Does this MR meet the acceptance criteria?

• Changelog entry added
• Documentation created/updated for this project, if necessary
• Tests added for this feature/bug
• Conforms to the code review guidelines
• Security reports checked/validated by reviewer