net/netmon: remove usage of direct callbacks from netmon (#17292)

The callback itself is not removed as it is used in other repos, making
it simpler for those to slowly transition to the eventbus.

Updates #15160

Signed-off-by: Claus Lensbøl <claus@tailscale.com>

log/sockstatlog/logger_test.go

@@ -24,7 +24,7 @@ func TestResourceCleanup(t *testing.T) {
 	if err != nil {
 		t.Fatal(err)
 	}
-	lg, err := NewLogger(td, logger.Discard, id.Public(), nil, nil)
+	lg, err := NewLogger(td, logger.Discard, id.Public(), nil, nil, nil)
 	if err != nil {
 		t.Fatal(err)
 	}