The family of a 10-year-old boy who sustained head injuries after an unidentified suspect drove an allegedly stolen cab portion of a semitrailer truck into his parents’ car has settled their lawsuit against the trucking company for $7 million.Kevin Gallegos, now 18, and his parents were driving southbound on California Avenue near 51st Street on June 25, 2010, heading to their grandmother’s house for dinner when, at the same time, a semi without its trailer attached was stolen from Ruan Transportation Corp. at …