Investigation of Santa Rosa's financially troubled Centennial Savings & Loan Assn. has turned up allegations of drug-money laundering, loan kickbacks and fraudulent real estate activities, and federal authorities said they suspect they have uncovered a major drug-money "laundering" operation. Centennial Savings was taken over in August, 1985, by the Federal Home Loan Bank board because it was financially insolvent, and former executive vice president Beverly Rose Haines, 54, and branch manager Raleigh R. Yasinitsky, 29, were arrested for embezzlement. Assistant U.S. Atty. Peter Robinson and John Phillips, head of the FBI's white-collar crime unit in San Francisco, said drug-money laundering was among the allegations being investigated, but emphasized that the probe is still in its preliminary stages.