Reduce the verbosity of test_store

The travis logs are going above 4Mb causing the builds to fail. One
test creates excessive output. This change reduces that output by approx
180k.

[extended tests]

Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Rich Salz <rsalz@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/5694)