Follow-up to #46337, same fix as #48280.

`title_bar` tests enable `remote/test-support`, which adds
`RemoteConnectionOptions::Mock`. But without
`recent_projects/test-support`, the match arms for that variant aren't
compiled, causing a non-exhaustive match error when testing the crate in
isolation:

```
error[E0004]: non-exhaustive patterns: `&RemoteConnectionOptions::Mock(_)` not covered
    --> crates/remote_connection/src/remote_connection.rs:233:76
```

CI doesn't catch this because `collab` and `sidebar` enable
`recent_projects/test-support` during workspace-wide tests.

Adding `remote_connection/test-support` instead isn't enough — that just
moves the same error into `recent_projects`.
`recent_projects/test-support` covers both.

Release Notes:

- N/A