rust: remove persons from crate owners

For historical reasons, the crates have a number of persons as owners, e.g.:

https://crates.io/crates/google-cloud-wkt/settings

Shows:

We should remove all the specific persons, and change this to a robot account or maybe two (for redundancy).

Start by locating the code or configuration that manages crate owners, then use the linked crates.io settings page as the model for checking affected crates. Inventory the current person owners and determine how the replacement robot account or accounts are configured; done means no specific persons remain and ownership is assigned to the chosen robot account arrangement.

Written by the indexing model from the issue text.