fix: geOrchestra json headers - organization as json payload is not transmitted

[pmauduit]

When the following configuration is set:

georchestra:
  gateway:
    default-headers:
      proxy: true
      username: true
      roles: true
      org: true
      orgname: true
      jsonUser: true
      jsonOrganization: true

The sec-organization base64-encoded JSON header is actually not provided. It looks like the organization is not fetched from the geOrchestra LDAP, hence the code not able to serialize it as expected.