Do not define L_ENDIAN (for now) when we guessed linux64-loongarch64

Do not define L_ENDIAN (for now) when we guessed linux64-loongarch64

In 160f48941d14 I made L_ENDIAN defined when the system is guessed to be
linux64-loongarch64.  Unfortunately now I found it problematic:

1. This should be added into Configurations/10-main.conf, not here.
   Having it here causes a different configuration when
   linux64-loongarch64 is explicitly specified than guessed.
2. With LTO enabled, this causes many test failures on
   linux64-loongarch64 due to #12247.

So I think we should remove it for now (master and 3.2 branch), and
reintroduce it to Configurations/10-main.conf when we finally sort
out #12247.

Reviewed-by: Matt Caswell <matt@openssl.org>
Reviewed-by: Tomas Mraz <tomas@openssl.org>
(Merged from https://github.com/openssl/openssl/pull/22812)