Update error response of validator publish endpoints (#557)

* Update error response for validator publish endpoints

* Fix refs to schema

Author: nflaig

apis/validator/aggregate_and_proofs.v2.yaml

@@ -31,7 +31,11 @@ post:
     "200":
       description: "Successful response"
     "400":
-      $ref: '../../beacon-node-oapi.yaml#/components/responses/InvalidRequest'
+      description: "Errors with one or more aggregate and proofs"
+      content:
+        application/json:
+          schema:
+            $ref: "../../beacon-node-oapi.yaml#/components/schemas/IndexedErrorMessage"
     "415":
       $ref: '../../beacon-node-oapi.yaml#/components/responses/UnsupportedMediaType'
     "500":

apis/validator/sync_committee_contribution_and_proof.yaml

@@ -17,6 +17,10 @@ post:
     "200":
       description: "Successful response"
     "400":
-      $ref: '../../beacon-node-oapi.yaml#/components/responses/InvalidRequest'
+      description: "Errors with one or more contribution and proofs"
+      content:
+        application/json:
+          schema:
+            $ref: "../../beacon-node-oapi.yaml#/components/schemas/IndexedErrorMessage"
     "500":
-      $ref: '../../beacon-node-oapi.yaml#/components/responses/InternalError'
+      $ref: '../../beacon-node-oapi.yaml#/components/responses/InternalError'