Add support for DAST 5 to the DAST CI templates

What does this MR do and why?

Updates the DAST CI templates to support both DAST version 4 and DAST version 5. The default version remains at version 4.

DAST version 5 names artifacts with the prefix gl-dast-, so gl-dast-*.* is set as the default artifact path. Checking presence of DAST_WEBSITE is removed because both DAST 4 and 5 make the same check inside the analyzer.

Templates affected:

• DAST.gitlab-ci.yml
• DAST.latest.gitlab-ci.yml
• DAST-On-Demand-Scan.gitlab-ci.yml

These changes are not considered to be breaking.

Reference

Build a DAST:5 release candidate (#456153 - closed)