guix: drop CMake workaround

We are now using 3.31.x.

contrib/guix/libexec/build.sh

@@ -272,10 +272,6 @@ mkdir -p "$DISTSRC"
     # Install built Bitcoin Core to $INSTALLPATH
     case "$HOST" in
         *darwin*)
-            # This workaround can be dropped for CMake >= 3.27.
-            # See the upstream commit 689616785f76acd844fd448c51c5b2a0711aafa2.
-            find build -name 'cmake_install.cmake' -exec sed -i 's| -u -r | |g' {} +
-
             cmake --install build --strip --prefix "${INSTALLPATH}" ${V:+--verbose}
             ;;
         *)