tests: prevent gitbuilder trigger in test-erasure-code.sh

Use the INFO keywork instead of WARNING so that gitbuilder does not
confuse this with a warning worth fixing.

Signed-off-by: Loic Dachary <loic@dachary.org>
Merge pull request #1989 from dachary/wip-8622-rados-alignment

tests: prevent gitbuilder trigger in test-erasure-code.sh

Reviewed-by: Lluis Pamies-Juarez <lluis@pamies.cat>