Minor: use ".touch" extension instead of ".new" in incremental compilation tests when it possible

jps-plugin/testData/incremental/withJava/javaUsedInKotlin/constantUnchanged/JavaClass.java.new

@@ -1,3 +0,0 @@
-public class JavaClass {
-    public static final String CONST = "A";
-}

jps-plugin/testData/incremental/withJava/javaUsedInKotlin/notChangeSignature/JavaClass.java.new

@@ -1,4 +0,0 @@
-public class JavaClass {
-    public static void foo() {
-    }
-}