[minor] IR: clean unnecessary ObsoleteDescriptorBasedAPI opt-ins

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/IrModuleDeserializer.kt

@@ -8,7 +8,6 @@ package org.jetbrains.kotlin.backend.common.serialization
 import org.jetbrains.kotlin.backend.common.serialization.encodings.BinarySymbolData
 import org.jetbrains.kotlin.descriptors.ModuleDescriptor
 import org.jetbrains.kotlin.ir.IrBuiltIns
-import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.declarations.*
 import org.jetbrains.kotlin.ir.symbols.*
 import org.jetbrains.kotlin.ir.util.IdSignature
@@ -94,7 +93,6 @@ abstract class IrModuleDeserializer(val moduleDescriptor: ModuleDescriptor, val
 }
 
 // Used to resolve built in symbols like `kotlin.ir.internal.*` or `kotlin.FunctionN`
-@OptIn(ObsoleteDescriptorBasedAPI::class)
 class IrModuleDeserializerWithBuiltIns(
     private val builtIns: IrBuiltIns,
     private val delegate: IrModuleDeserializer

compiler/ir/serialization.common/src/org/jetbrains/kotlin/backend/common/serialization/KotlinIrLinker.kt

@@ -308,7 +308,6 @@ abstract class KotlinIrLinker(
         return deserializerForModule.moduleFragment
     }
 
-    @OptIn(ObsoleteDescriptorBasedAPI::class)
     private fun maybeWrapWithBuiltInAndInit(
         moduleDescriptor: ModuleDescriptor,
         moduleDeserializer: IrModuleDeserializer