[Test] Replace public fun box() with fun box() in all box tests

compiler/testData/codegen/box/classes/kt1134.kt

@@ -3,7 +3,7 @@
 public class SomeClass() : java.lang.Object() {
 }
 
-public fun box():String {
+fun box():String {
     System.out?.println(SomeClass().getClass())
     return "OK"
 }

compiler/testData/codegen/box/classes/kt2482.kt

@@ -1,4 +1,4 @@
-public fun box() : String {
+fun box() : String {
     if ( 0 == 0 ) { // Does not crash if either this...
         if ( 0 == 0 ) { // ...or this is changed to if ( true )
             // Does not crash if the following is uncommented.

compiler/testData/codegen/box/classes/kt249.kt

@@ -7,7 +7,7 @@ class Outer() {
     }
 }
 
-fun box (): String {
+fun box(): String {
     val inner = Outer.Companion.Inner()
     return "OK"
 }

compiler/testData/codegen/box/classes/kt723.kt

@@ -1,6 +1,6 @@
 operator fun Int?.inc() : Int { if (this != null) return this.inc() else throw NullPointerException() }
 
-public fun box() : String {
+fun box() : String {
     var i : Int? = 10
     val j = i++
 

compiler/testData/codegen/box/classes/kt725.kt

@@ -1,6 +1,6 @@
 operator fun Int?.inc() = this!!.inc()
 
-public fun box() : String {
+fun box() : String {
     var i : Int? = 10
     val j = i++
 

compiler/testData/codegen/box/classes/kt903.kt

@@ -22,4 +22,4 @@ public open class PerfectNumberFinder() {
         }
 }
 
-fun box () = if (PerfectNumberFinder().isPerfect(28)) "OK" else "fail"
+fun box() = if (PerfectNumberFinder().isPerfect(28)) "OK" else "fail"