### What?
Ensure the Gravatar URL appends the query string only once.
### Why?
Previously `src` used `...?${query}` while `query` already began with
`?`, producing `??` and causing the avatar URL to be invalid in some
cases.
### How?
- Keep `query` as `?${params}` (from `URLSearchParams`).
- Change `src` from `https://www.gravatar.com/avatar/${hash}?${query}`
to `https://www.gravatar.com/avatar/${hash}${query}` so only one `?` is
present.
Fixes #13325