[clang][nullability] Remove old overload for getNullability()

clang/include/clang/AST/Type.h

#include "clang/Basic/OpenCLExtensionTypes.def"
   bool isLinkageValid() const;
 
   /// Determine the nullability of the given type.
   ///
   /// Note that nullability is only captured as sugar within the type
   /// system, not as part of the canonical type, so nullability will
   /// be lost by canonicalization and desugaring.
   Optional<NullabilityKind> getNullability() const;
-  // TODO: Remove overload.
-  Optional<NullabilityKind> getNullability(const ASTContext &) const;
 
   /// Determine whether the given type can have a nullability
   /// specifier applied to it, i.e., if it is any kind of pointer type.
   ///
   /// \param ResultIfUnknown The value to return if we don't yet know whether
   ///        this type can have nullability because it is dependent.
   bool canHaveNullability(bool ResultIfUnknown = true) const;
 

clang/lib/AST/Type.cpp

while (const auto *AT = Type->getAs<AttributedType>()) {
     // information.
     if (auto Nullability = AT->getImmediateNullability())
       return Nullability;
 
     Type = AT->getEquivalentType();
   }
   return std::nullopt;
 }
-// TODO: Remove overload.
-Optional<NullabilityKind> Type::getNullability(const ASTContext &) const {
-  return getNullability();
-}
 
 bool Type::canHaveNullability(bool ResultIfUnknown) const {
   QualType type = getCanonicalTypeInternal();
 
   switch (type->getTypeClass()) {
   // We'll only see canonical types here.
 #define NON_CANONICAL_TYPE(Class, Parent)       \
   case Type::Class:                             \