Remove configuration targets and related documentation for Guardian builds.

Remove configuration targets and related documentation for Guardian builds.

The intermediate configuration items to support Guardian builds are left
in place as a convenience for users who want to set up configurations
for Guardian on their own.

Fixes: #22175
Signed-off-by: Randall S. Becker <randall.becker@nexbridge.ca>
Reviewed-by: Richard Levitte <levitte@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
Reviewed-by: Tom Cosgrove <tom.cosgrove@arm.com>
Reviewed-by: Todd Short <todd.short@me.com>
(Merged from https://github.com/openssl/openssl/pull/24579)