feat(compass): remove upstreams/downstreams from UpsertEntityRequest (#477)

Lineage is now represented as edges with types derived_from and
generates, sent via UpsertEdge like all other relationships. This
removes the special-case handling where lineage was inlined on the
entity while all other edges used the edge API.

Author: ravisuhag

raystack/compass/v1beta1/service.proto

@@ -128,8 +128,10 @@ message UpsertEntityRequest {
   string description = 4;
   google.protobuf.Struct properties = 5;
   string source = 6;
-  repeated string upstreams = 7;
-  repeated string downstreams = 8;
+  // Fields 7, 8 removed: upstreams/downstreams are now represented as
+  // edges (derived_from / generates) via UpsertEdge.
+  reserved 7, 8;
+  reserved "upstreams", "downstreams";
 }
 
 message UpsertEntityResponse {