lineinfile combined with with_items was very inefficient for this task.
Given that each node's hostkey is added to every other host, it resulted
in O(n²) performance.
Additional networks per node also worsened the problem. For example, in
a 100 node deployment, with 4 networks per node, this task would need to
be executed 40,000 times (100 * 100 * 4).
Switching to use blockinfile brings the performance back to O(n), and
also removes any dependency on the number of networks per node. This
change also backports the task layout which improves general performance
and functionality of the role.
(cherry picked from commit 4157d7a5df)
Signed-off-by: Kevin Carter <email@example.com>