tests: unit: test_data_set: Remove unused mock
tests: unit: test_data_set: Remove unused mock

pjotrp/genenetwork2,genenetwork/genenetwork2,zsloan/genenetwork2,pjotrp/genenetwork2,zsloan/genenetwork2,pjotrp/genenetwork2,pjotrp/genenetwork2,pjotrp/genenetwork2,genenetwork/genenetwork2,zsloan/genenetwork2,genenetwork/genenetwork2,genenetwork/genenetwork2,zsloan/genenetwork2