repart: Use CRYPT_ACTIVATE_PRIVATE

Let's skip udev device scanning when activating a LUKS volume in
systemd-repart as we don't depend on any udev symlinks and don't
expect anything except repart to access the volume.

Suggested by systemd/systemd#33129 (comment).

(cherry picked from commit 726fc7a)
(cherry picked from commit d316aed)

Author: DaanDeMeyer

src/partition/repart.c

@@ -4002,7 +4002,7 @@ static int partition_encrypt(Context *context, Partition *p, PartitionTarget *ta
                                 dm_name,
                                 NULL,
                                 VOLUME_KEY_SIZE,
-                                arg_discard ? CRYPT_ACTIVATE_ALLOW_DISCARDS : 0);
+                                (arg_discard ? CRYPT_ACTIVATE_ALLOW_DISCARDS : 0) | CRYPT_ACTIVATE_PRIVATE);
                 if (r < 0)
                         return log_error_errno(r, "Failed to activate LUKS superblock: %m");