s4-torture: Add lease break retry tests - test4

s4-torture: Add lease break retry tests - test4

Test to see how the server behaves when the client flushes data back to
the server but doesn't send the lease break response over the channel.
Does it then retry the lease break?

This test is specifically expected to run against Samba and will not
work against a MS Windows servers because it uses the ignore method to
ignore oplock breaks sent by the server.

Signed-off-by: Guenther Deschner <gd@samba.org>
Signed-off-by: Sachin Prabhu <sprabhu@redhat.com>
Reviewed-by: Jeremy Allison <jra@samba.org>