core: Remove @Ignore annotations from TestHelper

TestHelper is not a test class (i.e., has no methods annotated with
@Test and does not extend the legacy org.junit.TestCase), so annotating
it or any of its methods with @Ignore is pointless.

Change-Id: Ibfa304bbaf1b20007ce1510d483dab395de2208b
Signed-off-by: Allon Mureinik <amureini@redhat.com>