SOLANA_CUDA=1 works again (#5968)

* SOLANA_CUDA=1 works again

* Minor comment reformat

* Set SOLANA_CUDA=1 explictly

multinode-demo/common.sh

@@ -55,8 +55,8 @@ else
     if [[ -n $NDEBUG ]]; then
       maybe_release=--release
     fi
-    declare manifest_path="--manifest-path=$SOLANA_ROOT/Cargo.toml"
-    printf "cargo run $manifest_path $maybe_release $maybe_package --bin %s %s -- " "$program" "$features"
+    declare manifest_path="--manifest-path=$SOLANA_ROOT/$crate/Cargo.toml"
+    printf "cargo $CARGO_TOOLCHAIN run $manifest_path $maybe_release $maybe_package --bin %s %s -- " "$program" "$features"
   }
 fi