fix: actions v2beta with api design for GA (#10303)

# Which Problems Are Solved

Actions v2beta API does not adhere to the [API
design](https://github.com/zitadel/zitadel/blob/main/API_DESIGN.md)
fully.

# How the Problems Are Solved

- Correct body usage for ListExecutions
- Correct REST path for ListTargets and ListExecutions
- Correct attribute names for ListTargetsResponse and
ListExecutionsResponse

# Additional Changes

- Remove unused object import.

# Additional Context

Closes #10138

---------

Co-authored-by: Marco A. <marco@zitadel.com>

internal/api/grpc/action/v2beta/query.go

@@ -52,7 +52,7 @@ func (s *Server) ListTargets(ctx context.Context, req *connect.Request[action.Li
 		return nil, err
 	}
 	return connect.NewResponse(&action.ListTargetsResponse{
-		Result:     targetsToPb(resp.Targets),
+		Targets:    targetsToPb(resp.Targets),
 		Pagination: filter.QueryToPaginationPb(queries.SearchRequest, resp.SearchResponse),
 	}), nil
 }
@@ -67,7 +67,7 @@ func (s *Server) ListExecutions(ctx context.Context, req *connect.Request[action
 		return nil, err
 	}
 	return connect.NewResponse(&action.ListExecutionsResponse{
-		Result:     executionsToPb(resp.Executions),
+		Executions: executionsToPb(resp.Executions),
 		Pagination: filter.QueryToPaginationPb(queries.SearchRequest, resp.SearchResponse),
 	}), nil
 }