NEW YORK (Reuters) -Wall Street’s biggest banks stockpiled more rainy-day funds to prepare for a possible recession and reported weak investment banking results while showing caution about forecasting income growth, as the economy remains uncertain. The outlook for big U.S. banks has been clouded by the Russia-Ukraine conflict and fading economic stimulus measures. Higher borrowing costs as the U.S. Federal Reserve hikes rates have also softened demand for mortgages and car loans. JPMorgan Chase & Co, Wells Fargo & Co and Bank of America Corp gave either disappointing or uncertain outlooks for…