CLI: remove obsolete language feature arguments

These arguments switch language features which cannot be disabled
anymore because they're enabled from some LV not later than 1.4, and the
minimal supported LV is currently 1.4.

compiler/tests-gen/org/jetbrains/kotlin/cli/CliTestGenerated.java

@@ -1195,11 +1195,6 @@ public class CliTestGenerated extends AbstractCliTest {
             runTest("compiler/testData/cli/jvm/useDeclarationThatWasExperimentalWithoutMarker.args");
         }
 
-        @TestMetadata("useMixedNamedArgumentsFlag.args")
-        public void testUseMixedNamedArgumentsFlag() throws Exception {
-            runTest("compiler/testData/cli/jvm/useMixedNamedArgumentsFlag.args");
-        }
-
         @TestMetadata("warningJdkWithNoJdk.args")
         public void testWarningJdkWithNoJdk() throws Exception {
             runTest("compiler/testData/cli/jvm/warningJdkWithNoJdk.args");