Migrate former Zemke-Rhyne secrets from a.b.c to a/b/c path

Summary:
Zemke-Rhyne secrets have been migrated to Vault under ops/secrets/<old name>.

Vault offers a concept of path to organize secrets a hierarchical way,
while under Zemke-Rhyne, the name of the secret used dots.

Ref T930

Test Plan: Refresh Vault policies, deploy a service on PaaS Docker

Reviewers: dereckson, ledesillusionniste

Reviewed By: dereckson

Maniphest Tasks: T930

Differential Revision: https://devcentral.nasqueron.org/D3302