Part 2 - Update snippets empty state text and buttons

• Part 1 - Improve Snippets form UX with description field (!24762 (merged))
• Part 2 - Update snippets empty state text and buttons (!24764 (merged))

What does this MR do?

This MR improves the UX of the snippets empty state by:

• Simplifying the empty state copy text
• Never show "Explore snippets" button because this feature is a bit flaky on .com
• Always show documentation button

Screenshots

Personal empty state	Project empty state

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

Closes #32714 (closed)