Make pipelineUrl nullable in DastProfileCreate

Background

a Dast::Profile is a description of how to run an on-demand dast scan. it is comprised of a name and description and is associated with both a DastSiteProfile and a DastScannerProfile.

What does this MR do?

fixes a mistake in ee-only the DastProfileCreate mutation that is currently behind the feature flag (dast_saved_scans).

Why?

this mutation may be used to create a Dast::Profile without running a scan (when run_after_create=false). in this instance, the pipelineUrl will be null.

Related Issue(s)

• #295244 (closed)

Notes

since this mutation is behind an unreleased feature flag, it does not represent a breaking change.

Does this MR meet the acceptance criteria?

Conformity

• Changelog entry featureflagdisabled
• 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