Migrate to math/rand/v2

[mx-psi]

Go 1.22 introduced math/rand/v2 which replaces the math/rand stdlib package. We should migrate to it!

Once we have migrated, we can forbid its usage via depguard.

Components using math/rand v1:

• exporter/exportertest
• receiver/receivertest

(generated using rg math/rand -l -tgo | cut -d'/' -f1-2 | sort | uniq | sed 's/^/- [ ] /')

Counterpart to open-telemetry/opentelemetry-collector-contrib/issues/34676.

[webstradev]

I can pick this up