[Test] Don't create separate .fir.txt file in BytecodeListingHandler if not necessary

compiler/fir/fir2ir/testData/codegen/bytecodeListing/properties/backingField/explicitBackingFieldsInJava.fir.txt

@@ -1,13 +0,0 @@
-@kotlin.Metadata
-public final class AC {
-    // source: 'AC.kt'
-    private final field number: int
-    public method <init>(): void
-    public final @org.jetbrains.annotations.NotNull method getNumber(): java.lang.Number
-}
-
-@kotlin.Metadata
-public interface AI {
-    // source: 'AI.kt'
-    public abstract @org.jetbrains.annotations.NotNull method getNumber(): java.lang.Number
-}

compiler/tests-common-new/tests/org/jetbrains/kotlin/test/backend/handlers/BytecodeListingHandler.kt

@@ -44,19 +44,29 @@ class BytecodeListingHandler(testServices: TestServices) : JvmBinaryArtifactHand
         if (multiModuleInfoDumper.isEmpty()) return
 
         val sourceFile = testServices.moduleStructure.originalTestDataFiles.first()
-        val extension =
+        val defaultTxtFile = sourceFile.withExtension(".txt")
-            if (testServices.defaultsProvider.defaultFrontend == FrontendKinds.FIR && FIR_IDENTICAL !in testServices.moduleStructure.allDirectives) ".fir.txt" else ".txt"
+        val irTxtFile = sourceFile.withSuffixAndExtension("_ir", ".txt")
-        val defaultTxtFile = sourceFile.withExtension(extension)
+        val firTxtFile = sourceFile.withExtension(".fir.txt")
+
+        val isFir = testServices.defaultsProvider.defaultFrontend == FrontendKinds.FIR
         val isIr = testServices.defaultsProvider.defaultTargetBackend?.isIR == true
-        val txtFile =
-            if (isIr) sourceFile.withSuffixAndExtension("_ir", extension).takeIf(File::exists) ?: defaultTxtFile
-            else defaultTxtFile
 
-        assertions.assertEqualsToFile(txtFile, multiModuleInfoDumper.generateResultingDump())
+        val actualFile = when {
+            isFir -> firTxtFile.takeIf { it.exists() } ?: irTxtFile.takeIf { it.exists() } ?: defaultTxtFile
+            isIr -> irTxtFile.takeIf { it.exists() } ?: defaultTxtFile
+            else -> defaultTxtFile
+        }
 
-        if (isIr && txtFile != defaultTxtFile) {
+        val goldenFile = when {
-            if (txtFile.readText() == defaultTxtFile.readText()) assertions.fail {
+            isFir -> irTxtFile.takeIf { it.exists() } ?: defaultTxtFile
-                "JVM and JVM_IR golden files are identical. Remove $txtFile."
+            else -> defaultTxtFile
+        }
+
+        assertions.assertEqualsToFile(actualFile, multiModuleInfoDumper.generateResultingDump())
+
+        if (actualFile != goldenFile) {
+            if (actualFile.readText().trim() == goldenFile.readText().trim()) assertions.fail {
+                "JVM and JVM_IR golden files are identical. Remove $actualFile."
             }
         }
     }