Follow-up from "Fix artifact downloads on Security tab"

The following discussion from !89217 (merged) should be addressed:

• @jiaan started a discussion:

  Suggestion (non-blocking / follow-up): This took me a while to understand. 😅 WDYT about making this condition more declarative through variable names? For example creating a computed prop to describe this.findArtifacts(SECURITY_REPORT_TYPE_ENUM_DAST).length > 0) and then referencing it here. I think it would help make this more maintainable.

How to set up and validate locally

1. Import the following gitlab project 2022-06-03_05-04-949_gitlab-examples_security_secur_export.tar.gz

2. Run the pipeline on master, wait for it to complete

3. Navigate to the pipeline page

4. Click on a single pipeline

5. Then click on the Security tab

6. Verify you can download each artifact

7. Verify artifact contents correspond to the report type