Create DAST API Template

What does this MR do?

Move DAST API into it's own CI template. This reduces complexity and makes a clear separation between the two products.

Related to #329155 (closed)

CI Templates

• A global test has been updated to allow DAST-API to not include stages and also not use a default stage name.
• Change is not backwards compatible. Luckily the documentation has yet to be published.
• Documentation has been updated in a separate MR. Documentation is still waiting on tech review, this change has been added to it.
• Tests have been updated for DAST, and added for DAST-API
• Test project for DAST
  • Project
  • CI Template
  • Job
  • 
• Test project for DAST API
  • Project
  • CI Template
  • Job
  • 

Screenshots (strongly suggested)

Does this MR meet the acceptance criteria?

Conformity

• 📋 Does this MR need a changelog?
  • I have included a changelog entry.
  • I have not included a changelog entry because _____.
• [-] 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