This commit removes the context as a param needed when calling methods
of HarnessNode. This change moves the context management inside
HarnessNode, aside from saving us a few lines, it makes the context
creation/timeout less error-prone.
This commit fixes the issue where a wrong context being inherited to
create a timeout context. When a parent context timed out, all its
children contexts also timed out, even the children contexts had a
larger timeout value. This means it only makes sense to inherite from a
parent when its children have smaller timeout value. Given the setup of
the itest, all the timeout contexts need to be created from a context
background(hence no timeout on the parent) unless there's an explicit
timeout bound we want to set.
In this commit, we put the context initialization inside
openChannelAndAssert, thus saving us a few lines and making sure the
context is always properly handled.
This commit refactored the function NewNode to take a *testing.T so that
the unexpected error is checked inside it. The caller is now free from
checking the errors.
