Delete marketing-site-LQA.md issue template
I propose we discontinue the LQA template (marketing-site-LQA.md), and let stakeholders/requestors use the generic localization-request.md template for both translation and review/LQA requests.
Reasons:
- The LQA process of the marketing website site, as described in this template (marketing-site-LQA.md), is outdated.
 - Also, looks like GitLab stakeholders are making LQA requests for non-marketing-website content, by still using this template: example 1, example 2.