Import tests cleanup

Removed 4 test cases:
ProtoTest.TD.MultiLangTests.TestImport.T006_BasicImport_TestFunction
ProtoTest.TD.MultiLangTests.TestImport.T021_Defect_1457354
ProtoTest.TD.MultiLangTests.TestImport.T021_Defect_1457354_2
ProtoTest.TD.MultiLangTests.TestImport.T021_Defect_1457354_3

Closed: http://adsk-oss.myjetbrains.com/youtrack/issue/MAGN-3938