Remove obsolete @OptIn(ExperimentalStdlibApi::class) annotations

They were added when `buildList`, `buildMap` and `buildSet` were experimental.

^KT-62510

compiler/frontend/src/org/jetbrains/kotlin/cfg/WhenChecker.kt

@@ -227,7 +227,6 @@ internal abstract class WhenOnClassExhaustivenessChecker : WhenExhaustivenessChe
 }
 
 private object WhenOnEnumExhaustivenessChecker : WhenOnClassExhaustivenessChecker() {
-    @OptIn(ExperimentalStdlibApi::class)
     override fun getMissingCases(
         expression: KtWhenExpression,
         context: BindingContext,
@@ -248,7 +247,6 @@ private object WhenOnEnumExhaustivenessChecker : WhenOnClassExhaustivenessChecke
 }
 
 internal object WhenOnSealedExhaustivenessChecker : WhenOnClassExhaustivenessChecker() {
-    @OptIn(ExperimentalStdlibApi::class)
     override fun getMissingCases(
         expression: KtWhenExpression,
         context: BindingContext,

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/tower/ResolvedAtomCompleter.kt

@@ -455,7 +455,6 @@ class ResolvedAtomCompleter(
         )
     }
 
-    @OptIn(ExperimentalStdlibApi::class)
     private fun KotlinType.replaceFunctionTypeArgumentsByDescriptor(descriptor: CallableDescriptor) =
         when (descriptor) {
             is CallableMemberDescriptor -> {