Ariana Grande was spotted out with her ex Ricky Alvarez in Texas before a concert in Austin ... sending fans into a frenzy and sparking romance rumors online ... but it's not what it looks like. Sources familiar with the situation tell TMZ ... Ari has friends in Austin for her birthday -- she turned 33 today -- and Ricky is one of the friends. They were snapped at a restaurant Thursday, but our sources insist there is nothing romantic between Ariana and Ricky this time around. Ari's in ATX for