[EXCEPTIONS] Distinguish onaptests and onapsdk exception

[EXCEPTIONS] Distinguish onaptests and onapsdk exception

there is no error_message method on onapsdk exception
as a consequence we may raise a new excpetion when catching sdk
exception leading to the non generation of the report

Issue-ID: TEST-332

Signed-off-by: morganrol <morgan.richomme@orange.com>
Change-Id: I42d1413ef142e29eeafdfe701f136ae45b097de4
(cherry picked from commit 0a9bc9eba1ada15ec1a2934f3baa465804f20e76)