[test] Fix sanity check for the OpenaccCudaCpp test

[vkarak]

Fixes MAINT-107.

@ajocksch Strangely the test fails with PrgEnv-gnu with the following error:

 MPI test on CPU using           12 tasks
 Result : FAIL
 Expected value sum(f3):    110.000000     actual value:   55.0000000

[teojgo]

Lgtm although I get the same failure with PrgEnv-gnu

[vkarak]

The test is not passing even on Daint with PrgEnv-gnu. I guess sth has changed in the test files. I'm doing git bisect to locate the exact commit now.

[vkarak]

This commit broke the test: 8623851

[lucamar]

@vkarak Merging #913 should bring the check back to its previous state

[vkarak]

Thanks, @lucamar. We will merge this after then.

[vkarak]

This PR is not needed anymore, since the problem is fixed in #913.