Rename `HoldsAbstract` to `IsAbstract`. #3501

Job	Run time
Go Build and Test	43s
CMake-macos-latest-Debug-clang	3m 20s
CMake-macos-latest-Release-clang	2m 40s
CMake-ubuntu-latest-Debug-gcc	1h 4m 25s
CMake-ubuntu-latest-Release-gcc	1h 6m 34s
CMake-windows-latest-Debug-msvc	38m 40s
CMake-windows-latest-Release-msvc	54m 34s
	3h 50m 56s

Provide feedback