chore: trace spans: use crypto/rand for generating them

math/rand.Read is deprecated in newer Go versions.

Also, it appears that crypto/rand is faster when used from multiple
goroutines: https://gist.github.com/problame/0699acd6f99db4163f26f0b8a61569f3

daemon/daemon.go

@@ -3,7 +3,6 @@ package daemon
 import (
 	"context"
 	"fmt"
-	"math/rand"
 	"os"
 	"os/signal"
 	"strings"
@@ -39,12 +38,6 @@ func Run(ctx context.Context, conf *config.Config) error {
 		cancel()
 	}()
 
-	// The math/rand package is used presently for generating trace IDs, we
-	// seed it with the current time and pid so that the IDs are mostly
-	// unique.
-	rand.Seed(time.Now().UnixNano())
-	rand.Seed(int64(os.Getpid()))
-
 	outlets, err := logging.OutletsFromConfig(*conf.Global.Logging)
 	if err != nil {
 		return errors.Wrap(err, "cannot build logging from config")