[IR] Mark methods with descriptors of ReferenceSymbolTable with @ObsoleteDescriptorBasedAPI

Also remove optIn annotation from IrPluginContext.symbolTable

plugins/scripting/scripting-compiler/src/org/jetbrains/kotlin/scripting/compiler/plugin/impl/KJvmReplCompilerBase.kt

@@ -26,6 +26,7 @@ import org.jetbrains.kotlin.config.languageVersionSettings
 import org.jetbrains.kotlin.descriptors.ScriptDescriptor
 import org.jetbrains.kotlin.diagnostics.impl.SimpleDiagnosticsCollector
 import org.jetbrains.kotlin.idea.MainFunctionDetector
+import org.jetbrains.kotlin.ir.ObsoleteDescriptorBasedAPI
 import org.jetbrains.kotlin.ir.backend.jvm.serialization.JvmDescriptorMangler
 import org.jetbrains.kotlin.ir.declarations.impl.IrFactoryImpl
 import org.jetbrains.kotlin.ir.util.SymbolTable
@@ -187,6 +188,7 @@ open class KJvmReplCompilerBase<AnalyzerT : ReplCodeAnalyzerBase>(
         return generationState
     }
 
+    @OptIn(ObsoleteDescriptorBasedAPI::class)
     private fun generateWithBackendIr(
         compilationState: ReplCompilationState<AnalyzerT>,
         sourceFiles: List<KtFile>,