Delete the sslprovider test

Delete the sslprovider test

This was added before the changes to the sslap/ssl_new/ssl_old tests which
run those tests with a non-default library context. It no longer adds
anything that those tests don't already do, so it can be deleted.

This also fixes a number of run-checker build failures which were failing
in this test if TLSv1.2 was disabled.

Reviewed-by: Richard Levitte <levitte@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/11832)