[libc++][math] Remove constrained overloads of std::{isnan, isinf, isfinite} (#106224)

## Why
Since #98841 and
#98952, the constrained
overloads are unused and not needed anymore as we added explicit
overloads for all floating point types. I forgot to remove them in the
mentioned PRs.

## What
Remove them.

Author: robincaloudis

libcxx/include/__math/traits.h

@@ -16,7 +16,6 @@
 #include <__type_traits/is_integral.h>
 #include <__type_traits/is_signed.h>
 #include <__type_traits/promote.h>
-#include <limits>
 
 #if !defined(_LIBCPP_HAS_NO_PRAGMA_SYSTEM_HEADER)
 #  pragma GCC system_header
@@ -45,12 +44,7 @@ _LIBCPP_NODISCARD inline _LIBCPP_HIDE_FROM_ABI bool signbit(_A1) _NOEXCEPT {
 
 // isfinite
 
-template <class _A1, __enable_if_t<is_arithmetic<_A1>::value && numeric_limits<_A1>::has_infinity, int> = 0>
-_LIBCPP_NODISCARD _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isfinite(_A1 __x) _NOEXCEPT {
-  return __builtin_isfinite((typename __promote<_A1>::type)__x);
-}
-
-template <class _A1, __enable_if_t<is_arithmetic<_A1>::value && !numeric_limits<_A1>::has_infinity, int> = 0>
+template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
 _LIBCPP_NODISCARD _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isfinite(_A1) _NOEXCEPT {
   return true;
 }
@@ -69,12 +63,7 @@ _LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI boo
 
 // isinf
 
-template <class _A1, __enable_if_t<is_arithmetic<_A1>::value && numeric_limits<_A1>::has_infinity, int> = 0>
-_LIBCPP_NODISCARD _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isinf(_A1 __x) _NOEXCEPT {
-  return __builtin_isinf((typename __promote<_A1>::type)__x);
-}
-
-template <class _A1, __enable_if_t<is_arithmetic<_A1>::value && !numeric_limits<_A1>::has_infinity, int> = 0>
+template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
 _LIBCPP_NODISCARD _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isinf(_A1) _NOEXCEPT {
   return false;
 }
@@ -98,11 +87,6 @@ _LIBCPP_NODISCARD inline _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI boo
 
 // isnan
 
-template <class _A1, __enable_if_t<is_floating_point<_A1>::value, int> = 0>
-_LIBCPP_NODISCARD _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnan(_A1 __x) _NOEXCEPT {
-  return __builtin_isnan(__x);
-}
-
 template <class _A1, __enable_if_t<is_integral<_A1>::value, int> = 0>
 _LIBCPP_NODISCARD _LIBCPP_CONSTEXPR_SINCE_CXX23 _LIBCPP_HIDE_FROM_ABI bool isnan(_A1) _NOEXCEPT {
   return false;