Add service to revoke DastSiteValidations

What does this MR do?

this merge request introduces a new ee-specific service called DastSiteValidations::RevokeService that deletes dast_site_validations where state=passed.

Why?

users need the ability to revoke permission to run an active (destructive) dast on-demand scan. this service will be used in a GraphQL mutation to facilitate this.

Related Issue(s)

• #280763 (closed)
• #276228 (closed)
• &4872 (closed)

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry developer-facing change only
• 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