ethers hook: reduce the probability of data loss

The hook was exiting immediately if lock was not acquired, entering a timed
loop to have more chances when acquiring the lock.

Signed-off-by: Luca Bigliardi <shammash@google.com>
Signed-off-by: Guido Trotter <ultrotter@google.com>
Reviewed-by: Guido Trotter <ultrotter@google.com>