set LogicalSize::cancel_wait_for_background_loop_concurrency_limit_se…

…maphore early

Before, walreceiver would already be running and hit the warning log
message that this patch also rectifies.

pageserver/src/tenant/timeline.rs

@@ -900,10 +900,10 @@ impl Timeline {
         background_jobs_can_start: Option<&completion::Barrier>,
         ctx: &RequestContext,
     ) {
+        self.spawn_initial_logical_size_computation_task(ctx);
         self.launch_wal_receiver(ctx, broker_client);
         self.set_state(TimelineState::Active);
         self.launch_eviction_task(background_jobs_can_start);
-        self.spawn_initial_logical_size_computation_task(ctx);
     }
 
     /// Graceful shutdown, may do a lot of I/O as we flush any open layers to disk and then
@@ -1777,7 +1777,7 @@ impl Timeline {
                 {
                     Some(cancel) => cancel.cancel(),
                     None => {
-                        warn!("unexpected: priority_tx not set, logical size calculation will not be prioritized");
+                        warn!("unexpected: cancel_wait_for_background_loop_concurrency_limit_semaphore not set, priority-boosting of logical size calculation will not work");
                     }
                 };
             }