*: update to etcd 3.5

[Quentin-M]

CHANGELOG

• Updates to etcd 3.5.0
• Adds address/port reuse now that support was added in etcd 3.5, avoiding "address already in use" issues between restarts/transitions on Kubernetes
• Switches mostly everything to Zap logger, and finally silences noisy clientv3 logs

[ironcladlou]

Thank you for separating the etcd 3.5 work from all the other fixes!

[Quentin-M]

@ironcladlou I'm thinking of creating a v3.4 branch, and renaming master to v3.5, any thoughts?

[ironcladlou]

@ironcladlou I'm thinking of creating a v3.4 branch, and renaming master to v3.5, any thoughts?

As long as there's some clear atomic commit where the 3.5 cutover happens (i.e. like you're doing in this PR) that's helpful from my POV... can always branch from it later. Either way is fine with me, I'm currently doing exploratory work and so don't have any processes built up around the project. I appreciate your consideration with the changes!