FIR: use ClassBuilderMode.FULL in FirMetadataSerializer

ABI is a special mode which is used only by the deprecated legacy
implementation of jvm-abi-gen. It is more reliable to use the standard
FULL mode to prevent divergence in behavior from normal compilation.

compiler/fir/fir2ir/jvm-backend/src/org/jetbrains/kotlin/fir/backend/jvm/FirMetadataSerializer.kt

@@ -10,7 +10,6 @@ import org.jetbrains.kotlin.backend.jvm.JvmLoweredDeclarationOrigin
 import org.jetbrains.kotlin.backend.jvm.metadata.MetadataSerializer
 import org.jetbrains.kotlin.codegen.ClassBuilderMode
 import org.jetbrains.kotlin.codegen.serialization.JvmSerializationBindings
-import org.jetbrains.kotlin.codegen.state.GenerationState
 import org.jetbrains.kotlin.config.*
 import org.jetbrains.kotlin.fir.FirSession
 import org.jetbrains.kotlin.fir.backend.Fir2IrComponents
@@ -92,7 +91,7 @@ fun makeLocalFirMetadataSerializerForMetadataSource(
         globalSerializationBindings,
         configuration.getBoolean(JVMConfigurationKeys.USE_TYPE_TABLE),
         targetId.name,
-        ClassBuilderMode.ABI,
+        ClassBuilderMode.FULL,
         configuration.getBoolean(JVMConfigurationKeys.DISABLE_PARAM_ASSERTIONS),
         session.languageVersionSettings.apiVersion >= ApiVersion.KOTLIN_1_4 &&
                 !configuration.getBoolean(JVMConfigurationKeys.NO_UNIFIED_NULL_CHECKS),