The charge that Quincy police Captain Michael Miller assaulted his pregnant wife was dismissed during a pretrial conference Thursday. “Without the victim’s testimony. . . there was insufficient evidence to go forward,” said Bridget Norton Middleton, assistant Plymouth district attorney. Miller has been on paid administrative leave since July 8, after allegedly assaulting his estranged wife, who is nine months pregnant, at her Plymouth home. Police Chief Paul Keenan said Miller will be back on active duty Friday at 8 a.m.