fix(install): actually invoke check_cxx_compiler in both install stages

Salvage follow-up for #88993: the preflight was defined but never
called from the prerequisites stage or the full-install path, so the
Fedora node-gyp failure (#93063) would still occur. Wire it in after
check_node in both sequences.

scripts/install.sh

@@ -3453,6 +3453,7 @@ run_stage_body() {
             check_python
             check_git
             check_node
+            check_cxx_compiler
             check_network_prerequisites
             install_system_packages
             ;;
@@ -3595,6 +3596,7 @@ main() {
     check_python
     check_git
     check_node
+    check_cxx_compiler
     check_network_prerequisites
     install_system_packages