Remove CMake settings that are no longer needed after reordering Guix build script to perform binary checks after installation.
Also removes unused CMake maintenance targets (check-security and check-symbols) and updates security checks to include libexec/ directory binaries (see PR #31679).
Remove CMAKE_SKIP_INSTALL_RPATH from CMakeLists.txt and add CMAKE_SKIP_RPATH to the Guix build script. This keeps build-environment-specific settings in the build scripts rather than hardcoded in the CMake configuration.