Remove "Module" from vulnerability feedback module name

What does this MR do?

This MR renames VulnerabilityFeedbackModule to VulnerabilityFeedback.

https://gitlab.com/gitlab-org/gitlab-ee/issues/11468

Does this MR meet the acceptance criteria?

Conformity

• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content