CMake config assumes gtest is installed in build directory if it detects it already installed

I have gtest already installed elsewhere in my build environment. Because of this, downloading and building gtest is skipped during the build stage. However during the install stage it assumes that because gtest was previously present, that it should be in build/RelWithDebInfo directory, causing the CMake to error out when attempting to copy the non-existent libraries to the install location.

Windows 10, MSVC 2019, Release 0.24.0