Remove snippet file_name in snippet lists

What does this MR do?

In this MR we remove the snippet file name from all the snippet lists, like in dashboard or explore. We discovered that, once we move all the snippets to repositories, it would be a heavy operation

Closes #215008 (closed)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content