bt2: update bindings to make test_component pass

bt2: update bindings to make test_component pass

This patch updates component.py such that the test_component test
passes.

With the API, it is no longer possible to obtain the graph from a
component, so things related to this are removed from both files.

Change-Id: I3ab0e6aaaa8ec1ad7378abb78072e6e130e1c2a4
Signed-off-by: Simon Marchi <simon.marchi@efficios.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1085
Tested-by: jenkins
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>