[K/N] Convert and enable some tests using System.out?.println()

^KT-59057

Merge-request: KT-MR-10546
Merged-by: Vladimir Sukharev <Vladimir.Sukharev@jetbrains.com>

compiler/testData/codegen/box/strings/kt889.kt

@@ -1,12 +1,4 @@
-// IGNORE_BACKEND: WASM
-// WASM_MUTE_REASON: IGNORED_IN_JS
-// IGNORE_BACKEND: JS_IR
-// IGNORE_BACKEND: JS_IR_ES6
-// TODO: muted automatically, investigate should it be ran for JS or not
-// IGNORE_BACKEND: JS, NATIVE
-
 operator fun Int.plus(s: String) : String {
-  System.out?.println("Int.plus(s: String) called")
   return s
 }