btrfs/011: increase the runtime for replace cancel

btrfs/011: increase the runtime for replace cancel

This test exercises the btrfs replace cancel path, but in order to do
this we have to have enough work to do in order to successfully cancel
the balance, otherwise the test fails because the operation has
completed before we're able to cancel.  This test has a very low pass
rate because we do not generate a large enough file system for replace
to have enough work, passing around 5% of the time.  Increase the time
spent to 10x the time we wait for the replace to start its work before
we cancel, this allows us to consistently pass this test.

Reviewed-by: Anand Jain <anand.jain@oracle.com>
Signed-off-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>