A politically wired Beacon Hill lobbying firm let off with a light penalty by Democratic gubernatorial hopeful Martha Coakley for a possible violation of state law hosted a fundraiser for Coakley’s U.S. Senate campaign in 2009, the Herald has learned.The fundraiser calls into question the attorney general’s repeated attempts to distance herself from the lobbying powerhouse, which negotiated a controversial settlement with Coakley’s office for allegedly charging illegal contingency fees to the Franciscan Hospital for Children.