97af652788 guix: Drop code for the unsupported `i686-linux-gnu` host (Hennadii Stepanov)
Pull request description:
Now GUIX build for the `i686-linux-gnu` host is broken, and [there are no plans to re-add it](https://github.com/bitcoin/bitcoin/pull/24448).
ACKs for top commit:
fanquake:
ACK 97af652788
Tree-SHA512: 968181aff65e607a7c1a1b06ac7dfd79f6e2ce49b3c4c3828def020e925769fdbab1859d37ea924ded7632405b30539ac3ec81ac714cb9a01a2f7d5c93301dd9