Re-evaluate RITM externalisation

[wpessers]

Is your feature request related to a problem? Please describe.
This issue is mainly for tracking. In #2037 we externalised the require-in-the-middle lib from our webpack bundle for the node.js layer, to fix an issue that broke instrumentation that relied on ritm hooking for non-core modules.

Describe the solution you'd like
Fixing upstream would be ideal, so that we can include RITM in our bundle again. In nodejs/require-in-the-middle#120 I offered some insight as well and proposed a solution that could possibly be implemented in the RITM lib.

Describe alternatives you've considered
Keeping RITM externalised.

_{Tip: React with 👍 to help prioritize this issue. Please use comments to provide useful context, avoiding +1 or me too, to help us triage it. Learn more here.}