chore: remove unnecessary time.Sleep for log flushing

The time.Sleep(100ms) after OpenTelemetry shutdown was removed as it's
not necessary for proper log writing. Zerolog automatically flushes logs
on program exit, and the remaining 1-second sleep for readiness
propagation is sufficient.

Tested that all shutdown logs are properly written without the sleep.

pkg/server/server.go

@@ -190,9 +190,6 @@ func (s *Server) Run() error {
 		}
 	}
 
-	// Force log flush
-	time.Sleep(100 * time.Millisecond)
-
 	// Return any server errors
 	if err, ok := <-serverErrors; ok {
 		return err