TEL AVIV, Israel, Jan. 5 —  Two suicide bombers blew themselves up minutes apart Sunday in a central Tel Aviv area crowded with foreign workers, killing at least 23 bystanders and wounding more than 100 people just three weeks before Israel’s general election. Hours later, Israeli attack helicopters fired at least four missiles at metal workshops in Gaza City, witnesses said. Eight people were slightly injured. The Israeli military said the workshops were used for making weapons, including mortars and rockets.