Truncate vulnerability title if longer than 255 characters

What does this MR do?

Related to https://sentry.gitlab.net/gitlab/gitlabcom/issues/1890490/?query=is%3Aunresolved%20security

We see number of errors when in security reports we have vulnerabilities with name/message longer than 255 (which is a limit in our database). To make sure we are saving these vulnerabilities into database we need to truncate them, because our security report schema is not validating maximum length of the title (https://gitlab.com/gitlab-org/security-products/security-report-schemas/-/blob/master/dist/dependency-scanning-report-format.json#L191).

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

Availability 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
• [-] Informed Infrastructure department of a default or new setting change, if applicable per definition of done

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