Removed specific MSVC settings when installing

[EduMenges]

When installing protobuf, it creates a different directory for CMake's config files when compiling with MSVC.

gRPC build on Windows

gRPC build on Linux and macOS

This is problematic because it requires conditionally setting its protobuf_DIR for different platforms:

if(MSVC)
    set(Protobuf_DIR "${PROTOBUF_PREFIX}/cmake")
else()
    set(Protobuf_DIR "${PROTOBUF_PREFIX}/lib/cmake/protobuf")
endif()

The original commit that made this based its choice on CMake's version 3.4, which not only is deprecated but is also based on a CMake version less than the one defined in the master file. Since then, CMake changed its behaviour, making this distinction unnecessary.