Chris Brown scored a small victory in his legal battle with a former housekeeper suing him over an alleged vicious dog attack ... a judge ruled the housekeeper will NOT be allowed to bring up his past arrest for assaulting Rihanna at their upcoming trial ... TMZ has learned. According to court docs, obtained by TMZ, the judge granted Chris' request to exclude any evidence about the infamous Rihanna assault from being introduced to the jury. Chris is being sued by Maria Avila , who claims in