endecode_test.c: Fix !fips v3.0.0 check

The fips_provider_version_* functions return true if the FIPS provider isn't
loaded.  This is somewhat counterintuitive and the fix in #25327 neglected
this nuance resulting in not running the SM2 tests when the FIPS provider
wasn't being loaded.

Reviewed-by: Viktor Dukhovni <viktor@openssl.org>
Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/25331)

(cherry picked from commit c6c6af18)