Remove gitlab-pages SERVER_WRITE_TIMEOUT config
What does this MR do?
Remove temporary fix to gitlab-pages large files download timeout. gitlab-pages now has a default SERVER_WRITE_TIMEOUT to "no timeout".
Related to: gitlab-org/gitlab-pages#725 (closed)
Author Check-list
Please read the Contributing document and once you do, complete the following:
- 
Assign to the correct reviewer per the contributing document 
- 
Apply the correct metadata per the contributing document 
- 
Link to related MRs for applying the changes on other environments 
- 
Link to related Chef changes 
- 
If necessary link to a Criticality 4 Change Request issue 
Reviewer Check-list
- 
Reviewed the diff jobs to confirm changes are as expected 
- 
No changes shown in the diffs not associated with this MR - This may require a rebase or further investigation 
Applier Check-list
- 
Make sure there is no ongoing deployment for the affected envs before merging (see #announcements slack channel)