[Test] Save IR bytecode dumps from BytecodeListingHandler to .ir.txt file instead of _ir.txt

This is needed to keep consistency with other dumps and to allow
  test helper plugin to recognize those dumps

compiler/testData/codegen/box/jvm8/defaults/nonDefaultInheritance/specialization.ir.txt

@@ -0,0 +1,47 @@
+Module: lib
+@kotlin.Metadata
+public interface Foo {
+    // source: 'Foo.kt'
+    public method foo(p0: java.lang.Object): java.lang.Object
+}
+
+@kotlin.Metadata
+public interface Foo2 {
+    // source: 'Foo.kt'
+    public method foo(p0: java.lang.Object): java.lang.Object
+}
+Module: main
+@kotlin.Metadata
+public final class DerivedClass {
+    // source: 'main.kt'
+    public method <init>(): void
+}
+
+@kotlin.Metadata
+public final class DerivedClassWithSpecialization {
+    // source: 'main.kt'
+    public method <init>(): void
+    public @org.jetbrains.annotations.NotNull method foo(@org.jetbrains.annotations.NotNull p0: java.lang.String): java.lang.String
+    public synthetic bridge method foo(p0: java.lang.Object): java.lang.Object
+    public final inner class DerivedInterface$DefaultImpls
+}
+
+@kotlin.Metadata
+public final class DerivedInterface$DefaultImpls {
+    // source: 'main.kt'
+    public static method foo(@org.jetbrains.annotations.NotNull p0: DerivedInterface, p1: java.lang.Object): java.lang.Object
+    public final inner class DerivedInterface$DefaultImpls
+}
+
+@kotlin.Metadata
+public interface DerivedInterface {
+    // source: 'main.kt'
+    public abstract method foo(p0: java.lang.Object): java.lang.Object
+    public final inner class DerivedInterface$DefaultImpls
+}
+
+@kotlin.Metadata
+public final class MainKt {
+    // source: 'main.kt'
+    public final static @org.jetbrains.annotations.NotNull method box(): java.lang.String
+}