Do not generate variables for non-generated fields

Use attributes instead of classes.
 #KT-43048 Fixed

compiler/testData/codegen/bytecodeListing/coroutines/coroutineFields_ir.txt

@@ -44,10 +44,9 @@ final class CoroutineFieldsKt$box$1 {
     enclosing method CoroutineFieldsKt.box()Ljava/lang/String;
     synthetic final field $result: kotlin.jvm.internal.Ref$ObjectRef
     field J$0: long
-    field L$0: java.lang.Object
+    private synthetic field L$0: java.lang.Object
     field L$1: java.lang.Object
     field label: int
-    private synthetic field p$: Controller
     inner (anonymous) class CoroutineFieldsKt$box$1
     method <init>(p0: kotlin.jvm.internal.Ref$ObjectRef, p1: kotlin.coroutines.Continuation): void
     public final @org.jetbrains.annotations.NotNull method create(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.NotNull p1: kotlin.coroutines.Continuation): kotlin.coroutines.Continuation

compiler/testData/codegen/bytecodeListing/coroutines/spilling/booleanParameter_ir.txt

@@ -20,7 +20,7 @@ final class BooleanParameterKt$box$1 {
 final class BooleanParameterKt$box$lambda$1 {
     // source: 'booleanParameter.kt'
     enclosing method BooleanParameterKt.box()Ljava/lang/String;
-    synthetic field it: boolean
+    synthetic field Z$0: boolean
     field label: int
     inner (anonymous) class BooleanParameterKt$box$lambda$1
     method <init>(p0: kotlin.coroutines.Continuation): void

compiler/testData/codegen/bytecodeListing/coroutines/spilling/component1_ir.txt

@@ -3,8 +3,8 @@
 final class Component1Kt$test$1 {
     // source: 'component1.kt'
     enclosing method Component1Kt.test()V
+    private synthetic field L$0: java.lang.Object
     field label: int
-    private synthetic field p$: Foo
     inner (anonymous) class Component1Kt$test$1
     method <init>(p0: kotlin.coroutines.Continuation): void
     public final @org.jetbrains.annotations.NotNull method create(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.NotNull p1: kotlin.coroutines.Continuation): kotlin.coroutines.Continuation

compiler/testData/codegen/bytecodeListing/coroutines/spilling/field_ir.txt

@@ -3,8 +3,8 @@
 final class FieldKt$test$1 {
     // source: 'field.kt'
     enclosing method FieldKt.test()V
+    private synthetic field L$0: java.lang.Object
     field label: int
-    private synthetic field p$: Foo
     inner (anonymous) class FieldKt$test$1
     method <init>(p0: kotlin.coroutines.Continuation): void
     public final @org.jetbrains.annotations.NotNull method create(@org.jetbrains.annotations.Nullable p0: java.lang.Object, @org.jetbrains.annotations.NotNull p1: kotlin.coroutines.Continuation): kotlin.coroutines.Continuation