Enable clippy::needless_update (#8830)

This PR enables the
[`clippy::needless_update`](https://rust-lang.github.io/rust-clippy/master/index.html#/needless_update)
rule and fixes the outstanding violations.

Release Notes:

- N/A

crates/collab/src/rpc.rs

@@ -3370,7 +3370,6 @@ fn build_update_user_channels(channels: &ChannelsForUser) -> proto::UpdateUserCh
             .collect(),
         observed_channel_buffer_version: channels.observed_buffer_versions.clone(),
         observed_channel_message_id: channels.observed_channel_messages.clone(),
-        ..Default::default()
     }
 }