Remove redundant context parameter

The methods _do_node_deploy() and _do_node_tear_down() is receiving the
context as a parameter but that's not used, and, as the methods already
receive task as another parameter the context is redudant because the
task object already have the context within it.

Change-Id: Ifdeb6e394d53e0a827af6eed36067ca402ba6054
Closes-Bug: #1372870
Merge "Remove redundant context parameter"