Before this change, the errors from tempest run are suppressed
in order to always execute cinderlib tests.
Use the variable exported by run-tempest instead,
and fail properly if needed.
This is a port of Ic1fd6fcc9b9183f195c66f0022e913ae9734c97b
from cinder-tempest-plugin.git to this repository.
Change-Id: I216a82a29c7fb6b1b2fac95b2a1af667c4e2b22d
(cherry picked from commit 7e04b5b0d4)
(cherry picked from commit 391f7c7f9b)
(cherry picked from commit 6fb0d93b3c)
(cherry picked from commit c29a6d087e)
070a0effbc