Extend early adopters feature set

What does this MR do?

Adds missing features that are present in EEP+EES that are not in early adopters.

Are there points in the code the reviewer needs to double check?

@DouweM @smcgivern Can you review it?

Does this MR meet the acceptance criteria?

• Changelog entry added, if necessary
• Documentation created/updated
• API support added
• Tests
  • Added for this feature/bug
  • All builds are passing
• Conform by the merge request performance guides
• Conform by the style guides
• Branch has no merge conflicts with master (if it does - rebase it please)
• Squashed related commits together

What are the relevant issue numbers?

Closes https://gitlab.com/gitlab-com/support-forum/issues/2398

mentioned in issue gitlab-com/support-forum#2398 (closed)

added 1 commit

• 2f836505 - Extend early adopters feature set

Compare with previous version

mentioned in issue gitlab-com/infrastructure#2691 (closed)

assigned to @stanhu

mentioned in commit 0af97abd

merged

@jivanvl @psimyn Please pick this into 9.5.3. :)

Picked into https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/2811, will merge into 9-5-stable-ee ready for 9.5.3-ee

removed Pick into Stable label

mentioned in commit d81b27ba

I'm not sure this, DB_LOAD_BALANCING_FEATURE, or REPOSITORY_SIZE_LIMIT_FEATURE are needed. Those aren't namespaced features anyway AFAIK.

mentioned in issue #3325 (closed)

mentioned in issue gitlab-com/support-forum#2412 (closed)