Send plan for spanner expansion to services-review

[data-sync-user]

Once the plan for the spanner expansion is in a good place lets send it to the services-review list for comments. https://groups.google.com/a/mozilla.com/g/services-review

┆Issue is synchronized with this Jira Task

[data-sync-user]

Wil Clouser commented from Jira:

[~accountid:5d264129831d7b0bcfbe3cfb] assigning to you since you’re the owner of the parent. Let’s make sure this goes out before we get too far into the epic. Thanks