Tests: fix stdlib declarations in IR interpreter test data

Fix some unresolved supertypes. This is necessary to be able to enable
IR fake override builder by default (KT-61514), because it traverses all
supertypes and asserts that they're classes, so that it can build fake
overrides for declarations from there. Without this change, for example
`IrFakeOverrideBuilder.buildFakeOverridesForClass` would crash.

compiler/testData/ir/interpreter/helpers/utils/kotlinUtils.kt

@@ -5,7 +5,7 @@ public inline val Char.code: Int get() = this.toInt()
 expect fun Double.isNaN(): Boolean
 expect fun Float.isNaN(): Boolean
 
-public data class Pair<out A, out B>(public val first: A, public val second: B) : Serializable {
+public data class Pair<out A, out B>(public val first: A, public val second: B) : java.io.Serializable {
     public override fun toString(): String = "($first, $second)"
 }
 
@@ -15,7 +15,7 @@ public fun <T> Pair<T, T>.toList(): List<T> = listOf(first, second)
 
 public data class Triple<out A, out B, out C>(
     public val first: A, public val second: B, public val third: C
-) : Serializable {
+) : java.io.Serializable {
     public override fun toString(): String = "($first, $second, $third)"
 }