[FEATURE]: Make Export CRD a single source-of-truth for service attributes

[zivnevo]

Currently, service attributes are taken from the Export CRD only on the server side.
On the client side, service attributes are taken from the Import CRD.
This may result in inconsistent policy decisions (same policy evaluates to different decisions on the two sides of the connection).

It is therefore required to have a single source of truth for service attributes, and it makes more sense to use the Export CRD for this purpose. However, this requires the Peer on the client side to get service attributes from the Peer on the server side.
We probably want to extend the heartbeat mechanism to support more requests.