Use common get_instance call in API plugins

Cleanup API to use common get_instance call which
automatically does exception handling. Not all cases
are handled in this patch as some require more
significant testcase rework and are done in future
patches to make it easier to review.

Change-Id: Id27350e6562636f81347b490db649744b6b41186
Merge "Use common get_instance call in API plugins"