Revert "Delay setting the sig algs until after the cert_cb has been called"

This reverts commit 524006dd1b80c1a86a20119ad988666a80d8d8f5.

While this change did prevent the sigalgs from getting inadvertently
clobbered by SSL_set_SSL_CTX(), it also caused the sigalgs to not be
set when the cert_cb runs.  This, in turn, caused significant breakage,
such as SSL_check_chain() failing to find any valid chain.  An alternate
approach to fixing the issue from #7244 will follow.

Reviewed-by: Matt Caswell <matt@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/9157)

(cherry picked from commit 6f34d7bc7d0c7fcd86c6f2772f26e42c925d8505)