riscv64: Replace id_rsa.pub with id_ed25519.pub

Encryption algorithm is changed after bumping to ubuntu:24:04,
ubuntu:22.04 is using RAS whicle ubuntu:24.04 is using Ed25519.

Replace `id_rsa.pub` with `id_ed25519.pub` to catch up.

Signed-off-by: Ruoqing He <heruoqing@iscas.ac.cn>

Author: RuoqingHe

riscv64/build_finalize.sh

@@ -13,7 +13,7 @@ echo 'tmpfs /tmp tmpfs rw,nosuid,nodev,size=524288k,nr_inodes=204800 0 0' >> $RO
 
 # Setup container ssh config
 yes "" | ssh-keygen -P ""
-cat /root/.ssh/id_rsa.pub > $ROOTFS_DIR/root/.ssh/authorized_keys
+cat /root/.ssh/id_ed25519.pub > $ROOTFS_DIR/root/.ssh/authorized_keys
 cat > /root/.ssh/config << EOF
 Host riscv-qemu
     HostName localhost