[Object,ELFTypes] Remove TargetEndianness

Finish the rename by #86604

Author: MaskRay

llvm/include/llvm/Object/ELFTypes.h

@@ -51,7 +51,6 @@ template <endianness E, bool Is64> struct ELFType {
   using packed = support::detail::packed_endian_specific_integral<Ty, E, 1>;
 
 public:
-  static const endianness TargetEndianness = E;
   static const endianness Endianness = E;
   static const bool Is64Bits = Is64;