“That the second proviso in section 28 of the Act of April 26, 1906, ch. 1876 (34 Stat. 148) [not classified to the Code], and the provisions contained in the fifth paragraph of section 17 of the Act of March 3, 1911, ch. 210 (36 Stat. 1070) [not classified to the Code], dealing with contracts made by the Choctaw and Chickasaw Tribes of Indians for professional legal services of attorneys, are hereby repealed.”