Attempt to update google-protobuf for migration-paths

Because the one we were using aren't compatible with
Ruby 2.5.3, and it'll be troublesome to switch Ruby.
Upgrading google-protobuf will be much easier.

All of them will need to be updated for Ruby 2.5.3

We remove oj because we don't really need it and it
doesn't compile on 2.5.3 with that version.

Closes https://gitlab.com/gitlab-org/gitlab-ce/issues/41825

https://docs.gitlab.com/ee/university/high-availability/aws

Now the rake task takes the path to the default storage directory.

Document that when updating using a Helm chart 'helm repo update' needs to be run before the 'helm upgrade ...' command.  

With an updated list of the images you need to change when switching to
the CE version.

Originally submitted at
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/6101

.

Signed-off-by: Rémy Coutable <remy@rymai.me>

Originally submitted at
https://gitlab.com/gitlab-org/gitlab-ee/merge_requests/6617

.

Signed-off-by: Rémy Coutable <remy@rymai.me>