Fix tests for server_send

[taqtiqa-mark]

Currently broken:

test tests/ui/server_send/ok/has-trace-field.rs [should pass] ... error                                    
┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈                         
error[E0432]: unresolved import `tracing_subscriber`             
  --> tests/ui/server_send/ok/has-trace-field.rs:16:9                              
   |                                                         
16 |     use tracing_subscriber::fmt;                               
   |         ^^^^^^^^^^^^^^^^^^ use of undeclared crate or module `tracing_subscriber`
                                                                                                 
error[E0433]: failed to resolve: use of undeclared crate or module `tracing_subscriber`
  --> tests/ui/server_send/ok/has-trace-field.rs:28:5               
   |                                                                                                        
28 |     tracing_subscriber::fmt()                                 
   |     ^^^^^^^^^^^^^^^^^^ use of undeclared crate or module `tracing_subscriber`
┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈┈