Remove hosted projects (#19754)

Release Notes:

- N/A

crates/proto/src/proto.rs

@@ -228,7 +228,6 @@ messages!(
     (JoinChannelChat, Foreground),
     (JoinChannelChatResponse, Foreground),
     (JoinProject, Foreground),
-    (JoinHostedProject, Foreground),
     (JoinProjectResponse, Foreground),
     (JoinRoom, Foreground),
     (JoinRoomResponse, Foreground),
@@ -411,7 +410,6 @@ request_messages!(
     (JoinChannel, JoinRoomResponse),
     (JoinChannelBuffer, JoinChannelBufferResponse),
     (JoinChannelChat, JoinChannelChatResponse),
-    (JoinHostedProject, JoinProjectResponse),
     (JoinProject, JoinProjectResponse),
     (JoinRoom, JoinRoomResponse),
     (LeaveChannelBuffer, Ack),