For provider tests, don't define a OPENSSL_NO_ macro

Since the macro to indicate if the test provider module is available
is local to the test programs, it's better to use a name that isn't
as easily confused with a library feature disabling macro that one
would expect to find in opensslconf.h.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/8664)