Node install script in Dockerfile runs a 60 second sleep

[This line](https://github.com/freeCodeCamp/rdb-alpha/blob/main/Dockerfile#L35) sleeps for 60 seconds along with a nag to move away from this method of installing Node.

Start at line 35 of Dockerfile and inspect the Node installation command, including its 60-second sleep and warning. Update the installation approach so the unnecessary wait and migration nag are removed, then rebuild the image to verify Node installation completes without the delay.

Written by the indexing model from the issue text.