Until now, we were never enabling this option in any test.
MBEDTLS_PSA_INJECT_ENTROPY requires MBEDTLS_NO_DEFAULT_ENTROPY_SOURCES, so
it cannot be enabled in the full config and it gets its own component.
Test with MBEDTLS_USE_PSA_CRYPTO enabled, since MBEDTLS_PSA_INJECT_ENTROPY
is a very PSA feature (which can break non-PSA applications), and Mbed
OS (for whch MBEDTLS_PSA_INJECT_ENTROPY was designed) enables
MBEDTLS_USE_PSA_CRYPTO when it enables MBEDTLS_PSA_INJECT_ENTROPY.
Signed-off-by: Gilles Peskine <Gilles.Peskine@arm.com>