Plan to release v3.5.31

### What would you like to be added? The etcd [patch release criteria] has been met for our `release-3.5` stable branch, so we should release `v3.5.31`. Work in progress CHANGELOG is: https://github.com/etcd-io/etcd/blob/main/CHANGELOG/CHANGELOG-3.5.md#v3531-tbc #### The list of commits included since the previous release is: [v3.5.30...release-3.5](https://github.com/etcd-io/etcd/compare/v3.5.30...release-3.5): <!-- START_PULL_REQUEST_LIST --> - #21728 - #21737 - #21769 - #21793 - #21820 <!-- END_PULL_REQUEST_LIST --> #### Outstanding tasks before releasing this version: - TBD #### Release team | GitHub handle | Role | |---|---| | @ivanvc | Release Lead | ### Why is this needed? Regular patch releases are vital to ensure our users have bug-free and secure software. [patch release criteria]: https://github.com/etcd-io/etcd/blob/main/Documentation/contributor-guide/release.md#patch-release-criteria