Analytics: resolve redundant-hostnames warning

This is the warning

> Property grpc is receiving data from redundant hostnames. Some of the redundant hostnames are:
> - grpc.io
> - www.grpc.io
> Redundant hostnames are counted as separate rows in reports, so hits that are going to the same page on your site from different hostnames will be split into multiple rows. With data split across multiple rows, traffic to specific pages will appear lower than it actually is.
>
> To avoid this problem, consider setting up a 301 redirect from one of your redundant hostnames to the other, or create a search-and-replace filter that strips "www." from hostnames.
>
> [Google Tag Assistant Recordings](https://analytics.google.com/tagrecordings/notificationlink?utm_source=google.com&utm_medium=notif_referral&utm_campaign=DUPLICATE_HOSTNAMES) can help you verify that your redirect is setup correctly, or that your filter is working as intended.

For details about filters, see [Search-and-replace filters](https://support.google.com/analytics/answer/1034834?hl=en#zippy=%2Cin-this-article).