monitoring: do not use a separate go.mod/go.sum file

Created by: slimsag

The monitoring generator used a seperate go.mod since it must have one for dependency pinning when we transfer it to Docker as the build context (unless we transfer the entire repo as build context, which is not ideal). However, this seperate go.mod meant that sometimes when editing the monitoring generator's files in e.g. VS Code the tooling would (unfortunately) modify the root go.mod/go.sum instead of the one in the monitoring directory. To workaround this, this change switches us to using the root's and just copying it into the Docker container when needed.