Don't restrict the ECDSA settable ctx params unnecessarily

We just allow all possible settables all the time. Some things like the
digest name can't actually be changed in some circumstances - but we already
have checks for those things. It's still possible to pass a digest of the
same name to one that's already been set for example.

Fixes #25012

Reviewed-by: Dmitry Belyavskiy <beldmit@gmail.com>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/25057)

(cherry picked from commit d244abb6)