Undeprecate VariableDescriptorWithAccessors.isDelegated

Apparently there's quite a few valid usages of this method outside of
the compiler frontend, where manual suppression is annoying.

compiler/frontend/src/org/jetbrains/kotlin/descriptors/impl/LocalVariableDescriptor.java

@@ -108,10 +108,7 @@ public class LocalVariableDescriptor extends VariableDescriptorWithInitializerIm
         return setter;
     }
 
-    // This override is not deprecated because local variables can only come from sources,
-    // and we can be sure that they won't be recompiled independently
     @Override
-    @SuppressWarnings("deprecation")
     public boolean isDelegated() {
         return isDelegated;
     }

compiler/frontend/src/org/jetbrains/kotlin/resolve/calls/smartcasts/DataFlowValueKindUtils.kt

@@ -41,7 +41,6 @@ internal fun VariableDescriptor.variableKind(
         return propertyKind(usageModule)
     }
 
-    @Suppress("DEPRECATION")
     if (this is LocalVariableDescriptor && this.isDelegated) {
         // Local delegated property: normally unstable, but can be treated as stable in legacy mode
         return if (languageVersionSettings.supportsFeature(LanguageFeature.ProhibitSmartcastsOnLocalDelegatedProperty))