fixed test_batch_unlock
fixed test_batch_unlock

The secret registration was being done before the channel was close,
that create a race which made the test fail with the matrix transport.
The test failed because the nodes learned about the secret and unlocked
the transfer off-chain before the channel was closed, making the batch
unlock unecessary, and therefor the test failed.

[ci integration]

hackaugusto/raiden,hackaugusto/raiden