[raft] Remove locality and random packages and precompute ID

[MariemBaccari]

Following the efforts of pre-computing and validating as much as possible before proposing (e.g. #1714), this PR:

• Removes the locality package which was unused since RID payloads now encapsulate the writer directly.
• Removes the random package and precomputes the implicit subscription UUID.

[mickmis]

LGTM - the best kind of PRs :D

[mickmis]

@MariemBaccari looks like that with this the Locality flag is not required anymore in Proposal, and that it is then not required to pass it down from Init. If that's correct could you follow-up with that cleanup?

[MariemBaccari]

@mickmis It is not used anymore indeed. However, it might be useful for observability to track locality in addition to the node ID for each proposal. What do you think ?

[mickmis]

@mickmis It is not used anymore indeed. However, it might be useful for observability to track locality in addition to the node ID for each proposal. What do you think ?

One way or another we probably want to surface the locality at some point. Now, it is more of a free-text value configured at each node rather than an authoritative information. That would be coming from the certificate. The point I want to make here is that it is unclear now this is how we want to identify participants, and it might be misleading to include that already now. So I'd rather favor removing that field from the proposal for now and add it back later if that is needed. That will be much easier than removing it later if it ends up not being required.

[MariemBaccari]

@mickmis That's a great point, I just opened #1752 to remove the locality :)