Cleanup s390x exclude test list with build-gcs tests
Cleanup s390x exclude test list with build-gcs tests

As per https://github.com/tektoncd/pipeline/pull/3771 build-gcs
support(and tests) was removed. The tests were in exclude list for
s390x. Now the list can be reduced.

Signed-off-by: Yulia Gaponenko <4e1e642fe1866b37c57d72b7676d11bb58a731a1@de.ibm.com>

tektoncd/pipeline,tektoncd/pipeline