[FIR2IR] Use FIR-specific methods to search for overridden functions

compiler/testData/codegen/box/builtinStubMethods/substitutedListWithExtraSuperInterface.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // TARGET_BACKEND: JVM
 
 // FILE: Test.java

compiler/testData/codegen/box/collections/noStubsInJavaSuperClass.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // TARGET_BACKEND: JVM
 
 // FILE: B.java

compiler/testData/codegen/box/collections/strList.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // TARGET_BACKEND: JVM
 
 // FILE: J.java

compiler/testData/codegen/box/coroutines/createCoroutinesOnManualInstances.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // KJS_WITH_FULL_RUNTIME
 // IGNORE_BACKEND: JS_IR
 // IGNORE_BACKEND: JS_IR_ES6

compiler/testData/codegen/box/inlineClasses/functionNameMangling/overridingMethodInGenericClass2.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +InlineClasses
-// IGNORE_BACKEND_FIR: JVM_IR
 
 abstract class GenericBase<T> {
     abstract fun foo(x: T): T

compiler/testData/codegen/box/inlineClasses/inlineClassImplementsCollection.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +InlineClasses
-// IGNORE_BACKEND_FIR: JVM_IR
 // WITH_RUNTIME
 // TARGET_BACKEND: JVM
 

compiler/testData/codegen/box/sam/partialSam.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +NewInference +SamConversionPerArgument
-// IGNORE_BACKEND_FIR: JVM_IR
 // TARGET_BACKEND: JVM
 // WITH_RUNTIME
 // FILE: Fn.java

compiler/testData/codegen/box/sam/partialSamKT.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +NewInference +SamConversionForKotlinFunctions +SamConversionPerArgument
-// IGNORE_BACKEND_FIR: JVM_IR
 // TARGET_BACKEND: JVM
 // WITH_RUNTIME
 // FILE: Fn.java

compiler/testData/codegen/box/specialBuiltins/removeSetInt.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 // KJS_WITH_FULL_RUNTIME
 // IGNORE_BACKEND: NATIVE
 class MySet : HashSet<Int>() {