Vornado Realty Trust said Monday that its 53% owned joint venture has completed a $250-million refinancing of 7 W. 34th St., a 477,000-square-foot Class A Manhattan office building. Amazon leases all the office space at the property. The non-recourse, five-year interest-only loan matures in February 2031 and has a fixed rate of 5.79%. The JV paid …