Remove workaround for DevCom-1044530

[CaseyCarter]

DevCom-1044530 / VSO-1130458 "long <=> double works, but not in a concept" has been fixed for VS 2019 16.8p3. When that preview ships and becomes our toolset compiler, we'll be able to remove the workaround from tests/std/tests/P0896R4_P1614R2_comparisons:

STL/tests/std/tests/P0896R4_P1614R2_comparisons/test.cpp

Lines 263 to 265 in 896e137

	#if defined(__clang__) || defined(__EDG__) // TRANSITION, DevCom-1044530
	STATIC_ASSERT(test_compare_three_way<long, double, partial_ordering>());
	#endif // TRANSITION, DevCom-1044530