Re-remove peer-service-mapping declarative_name from r2dbc metadata

The declarative_name was previously removed in bbca603 to fix the
DeclarativeConfigValidationTest, but it was reintroduced when merging
upstream/main (which still carried the line). Remove it again.

Author: trask

instrumentation/r2dbc-1.0/metadata.yaml

@@ -29,7 +29,6 @@ configurations:
     type: boolean
     default: false
   - name: otel.instrumentation.common.peer-service-mapping
-    declarative_name: java.common.service_peer_mapping
     description: Used to specify a mapping from host names or IP addresses to peer services.
     type: map
     default: ""