KT-7151 Convert 'System.out.println()' to just 'println()'

#KT-7151 Fixed

j2k/testData/fileOrElement/nullability/FieldComparedWithNull.kt

@@ -4,7 +4,7 @@ class C {
 
     fun foo() {
         if (s == null) {
-            System.out.print("null")
+            print("null")
         }
     }
 }

j2k/testData/fileOrElement/nullability/FieldComparedWithNull2.kt

@@ -2,7 +2,7 @@ class C(private val s: String?) {
 
     fun foo() {
         if (s != null) {
-            System.out.print("not null")
+            print("not null")
         }
     }
 }

j2k/testData/fileOrElement/nullability/FieldComparedWithNull3.kt

@@ -5,7 +5,7 @@ class C {
 class D {
     fun foo(c: C) {
         if (null == c.s) {
-            System.out.println("null")
+            println("null")
         }
     }
 }

j2k/testData/fileOrElement/nullability/FieldComparedWithNull4.kt

@@ -2,7 +2,7 @@ class C(private val s: String?) {
 
     init {
         if (s == null) {
-            System.out.print("null")
+            print("null")
         }
     }
 }

j2k/testData/fileOrElement/nullability/NullableVariableDotAccess.kt

@@ -1,5 +1,5 @@
 fun foo(s: String?, b: Boolean): Int {
-    if (s == null) System.out.println("null")
+    if (s == null) println("null")
     if (b) return s!!.length()
     return 10
 }