[FIR] Improve mapping arguments to parameters

compiler/testData/codegen/box/mixedNamedPosition/defaults.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +NewInference +MixedNamedArgumentsInTheirOwnPosition
-// IGNORE_BACKEND_FIR: JVM_IR
 
 fun foo(
     p1: Int = 1,

compiler/testData/codegen/box/mixedNamedPosition/simple.kt

@@ -1,5 +1,4 @@
 // !LANGUAGE: +NewInference +MixedNamedArgumentsInTheirOwnPosition
-// IGNORE_BACKEND_FIR: JVM_IR
 
 fun foo(
     p1: Int,

compiler/testData/codegen/box/vararg/kt6192.kt

@@ -1,4 +1,3 @@
-// IGNORE_BACKEND_FIR: JVM_IR
 fun barB(vararg args: Byte) = args
 fun barC(vararg args: Char) = args
 fun barD(vararg args: Double) = args

compiler/testData/codegen/box/vararg/singleAssignmentToVarargsInFunction.kt

@@ -1,4 +1,5 @@
 // !LANGUAGE: -ProhibitAssigningSingleElementsToVarargsInNamedForm
+// IGNORE_BACKEND_FIR: JVM_IR
 
 fun box(): String {
     if (test1(p = 1) != "1") return "fail 1"