[dev-portal] Update developer-portal RDS CA cert

[limed]

The AWS RDS CA certificate which we are currently using on the developer-portal RDS instances is set to expire on March 5th 2020 and AWS is telling us to migrate off this certificate Feb 4th 2020 to a newer CA cert, we should however do this earlier if we can. This update will require an RDS reboot and therefore we need to schedule some downtime for this

Instructions:
https://docs.aws.amazon.com/AmazonRDS/latest/UserGuide/UsingWithRDS.SSL-certificate-rotation.html

Database affected:

• developer-portal-prod
• developer-portal-stage

[limed]

All done