ZTS: Reduce file size in redacted_panic to 1GB

This test takes 3 minutes on RELEASE FreeBSD bots, but on CURRENT,
probably due to debugging it has in kernel, it does not complete
within 10 minutes, ending up killed.  As I see all the redacting
here happens within the first ~128MB of the file, so I hope it
won't matter if there is 1GB of data instead of 2GB.

Signed-off-by:	Alexander Motin <[email protected]>
Sponsored by:	iXsystems, Inc.

Author: amotin

tests/zfs-tests/tests/functional/redacted_send/redacted_panic.ksh

@@ -39,7 +39,7 @@ function cleanup
 log_onexit cleanup
 
 log_must zfs create -o recsize=8k $sendfs
-log_must dd if=/dev/urandom of=/$sendfs/file bs=1024k count=2048
+log_must dd if=/dev/urandom of=/$sendfs/file bs=1024k count=1024
 log_must zfs snapshot $sendfs@init
 log_must zfs clone $sendfs@init $clone
 log_must stride_dd -i /dev/urandom -o /$clone/file -b 8192 -s 2 -c 7226