add headless as a config

[wordpressfan]

Description

When I was playing with tests here I wanted to change this headless option on/off many times so having it as a config will make that easier.

Type of change

Please delete options that are not relevant.

• Enhancement (non-breaking change which improves an existing functionality).

Is the solution different from the one proposed during the grooming?

It's not groomed and doesn't have an issue, I found it as a quick win PR.

Checklists

Generic development checklist

• My code follows the style guidelines of this project, with adapted comments and without new warnings.
• I have added unit and integration tests that prove my fix is effective or that my feature works.
• The CI passes locally with my changes (including unit tests, integration tests, linter).
• Any dependent changes have been merged and published in downstream modules.
• If applicable, I have made corresponding changes to the documentation. Provide a link to the documentation.

Test summary

• I triggered all changed lines of code at least once without new errors/warnings/notices.
• I validated all Acceptance Criteria of the related issues. (If applicable, provide proof).
• I validated all test plan the QA Review asked me to.

If not, detail what you could not test.

Please describe any additional tests you performed.

The base branch was changed.