Update QA selector for snippet desccription

What does this MR do?

Updates snippet description QA selector to fix the create_snippet_spec.rb

Relates to #215031 (closed)

Follow-up on !29985 (merged)

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