FindGLUT: Drop the now-unnecessary exclusion of pkg-config for multiconfig

Revert commit e0a62b84b5 (FindGLUT: On Windows and with multiple config
generator do not use pkg-config, 2022-09-27, v3.25.0-rc1~69^2). We now
call `select_library_configurations()` even after using pkg-config,
which will handle the absent libraries on Debug/Release configurations.

Issue: #24028