Correct all references to gitlab-ce and gitlab-ee

What does this MR do?

This changes any mention of gitlab-ce to gitlab-foss, and any mention of gitlab-ee to just gitlab. In the locale files there are still some references to the Crowdin project names. I have left these as-is, since this is not tied to the repository but the distribution.

Does this MR meet the acceptance criteria?

Conformity

• Documentation created/updated or follow-up review issue created
• Code review guidelines
• Merge request performance guidelines
• Style guides
• Database guides
• Separation of EE specific content