She worked for George Schaefer ("Hallmark Hall of Fame") and Quinn Martin ("Streets of San Francisco") following stints as a producer on and off-Broadway.Sybil Trubin, who worked as a business executive for television producers George Schaefer and Quinn Martin in an era when few women held such a post in Hollywood, has died. She was 88. Trubin, who also produced plays for Broadway and off-Broadway, died Nov. 3 at her…