clientv3/client.go
func NewCtxClient(ctx context.Context) *Client {
	cctx, cancel := context.WithCancel(ctx)
	return &Client{ctx: cctx, cancel: cancel}
}
func NewCtxClient(ctx context.Context) *Client {
	cctx, cancel := context.WithCancel(ctx)
	return &Client{ctx: cctx, cancel: cancel}
}
// NewCtxClient creates a client with a context but no underlying grpc
// connection. This is useful for embedded cases that override the
// service interface implementations and do not need connection management.