Replace nsenter with reexec

### What is the problem you're trying to solve

We currently depend on the nsenter binary.

Although working, this is problematic for a couple of reasons:
- different distro (busybox) may have different syntax
- different versions may or may not support different flags
- nsenter is a bit of a blackbox, and it is not trivial to figure out what happens when you pass `-w` vs. `-W` for example

Linking ticket #3385 for example.

### Describe the solution you'd like

An alternative solution would be to reexec instead, possibly leveraging docker reexec package.

This is certainly a somewhat complex endeavor, and definitely impactful from a security standpoint. It has to be done right.

### Additional context

_No response_