Update SSL cert for user-content.gitlab-static.net

Production Change - Criticality 2 C2

Change Objective	Describe the objective of the change
Change Type	Operation
Services Impacted	Camoproxy - user-content.gitlab-static.net
Change Team Members	@bjk-gitlab, @ggillies
Change Criticality	C2
Change Reviewer	@igorwwwwwwwwwwwwwwwwwwww
Tested in staging	#2189 (closed)
Dry-run output
Due Date	2020-08-27
Time tracking	To estimate and record times associated with changes ( including a possible rollback )

Detailed steps for the change

• Target apply the certificate gprd-camo-proxy with tf apply -target=module.camoproxy-lb.google_compute_managed_ssl_certificate.default.
• Manually associate gprd-camo-proxy with the GCP load-balancer frontend.
• Wait 30 minutes for GCP to provision and rollout additional certificate.
• Target apply the certificate list swap with tf apply -target=module.camoproxy-lb.
• Verify Terraform Plan NOOP.

Rollback steps

• Rollback https://ops.gitlab.net/gitlab-com/gitlab-com-infrastructure/-/merge_requests/1771
• Apply TF to return to manually managed cert.

Changes checklist

• Detailed steps and rollback steps have been filled prior to commencing work
• SRE on-call has been informed prior to change being rolled out
• There are currently no open issues labeled as ServiceMonitoring with severities of ~S1 or ~S2