No services visible when created before automatic secret creation

Hi,

PR #424 added the creation of a secret for each service installation in Onyxia, and PR #444 uses this secret for service visibility in projects namespace.
For services installed before the first PR in project namespace, they don't get listed by the API (so don't appear in the `My Service` Page of Onyxia).
A way to fix this is to add the missing secret (in the same way onyxia does).