[FIR] Remove redundant opt-ins to ExperimentalStdlibApi in FIR modules

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/FirJavaElementFinder.kt

@@ -47,7 +47,6 @@ class FirJavaElementFinder(
 ) : PsiElementFinder(), KotlinFinderMarker {
     private val psiManager = PsiManager.getInstance(project)
 
-    @OptIn(ExperimentalStdlibApi::class)
     private val firProviders: List<FirProvider> = buildList {
         add(session.firProvider)
         session.collectAllDependentSourceSessions().mapTo(this) { it.firProvider }

compiler/fir/java/src/org/jetbrains/kotlin/fir/java/scopes/JavaClassStaticUseSiteScope.kt

@@ -79,7 +79,6 @@ class JavaClassStaticUseSiteScope internal constructor(
         return result
     }
 
-    @OptIn(ExperimentalStdlibApi::class)
     override fun getCallableNames(): Set<Name> {
         return buildSet {
             addAll(declaredMemberScope.getCallableNames())
@@ -89,7 +88,6 @@ class JavaClassStaticUseSiteScope internal constructor(
         }
     }
 
-    @OptIn(ExperimentalStdlibApi::class)
     override fun getClassifierNames(): Set<Name> {
         return buildSet {
             addAll(declaredMemberScope.getClassifierNames())