Change vulnerability name to message

What does this MR do?

For vulnerabilities on dependency list view https://gitlab.com/gitlab-org/gitlab-ee/issues/10077 we show information about its name and severity. After some testing we found out that:

1. Some vulnerabilities don't have name field
2. On security dashboard we show not name but message. https://gitlab.com/gitlab-org/gitlab-ee/blob/6273c3c396a6a6d87e53831e28ad30596ab220de/ee/lib/gitlab/ci/parsers/security/common.rb#L51

So this MR aims to reduce confusion between two pages and fix bug when vulnerability name is empty on dependency list

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry
• 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

Performance and Testing

• Review and add/update tests for this feature/bug. Consider all test levels. See the Test Planning Process.
• Tested in all supported browsers

Security

If this MR contains changes to processing or storing of credentials or tokens, authorization and authentication methods and other items described in the security review guidelines:

• Label as security and @ mention @gitlab-com/gl-security/appsec
• The MR includes necessary changes to maintain consistency between UI, API, email, or other methods
• Security reports checked/validated by a reviewer from the AppSec team