git-artifacts: _really_ stop building i686 artifacts except mingit

As announced multiple times and also documented in detail at
https://gitforwindows.org/32-bit, Git for Windows will no longer
publish 32-bit installers, portable Gits and such.

The only i686 artifacts that will be published are the MinGit ones,
until April 2029.

In d308f34 (git-artifacts: stop building i686 artifacts except mingit,
2025-02-25), I already tried to address this. But I forgot that the
default, if left unspecified which artifacts to build, is to build all
of them (with "all" being hard-coded also in the `Configure environment`
step of the `git-artifacts` workflow).

So let's adjust this step, too.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>

Author: dscho

.github/workflows/git-artifacts.yml

@@ -167,7 +167,8 @@ jobs:
           echo "MINGW_PACKAGE_PREFIX=$MINGW_PACKAGE_PREFIX" >> $GITHUB_OUTPUT
           echo "SDK_REPO_ARCH=$SDK_REPO_ARCH" >> $GITHUB_OUTPUT
           test -n "$ARTIFACTS_TO_BUILD" || {
-            ARTIFACTS_TO_BUILD="installer portable archive mingit"
+            ARTIFACTS_TO_BUILD="mingit"
+            test "$ARCHITECTURE" = i686 || ARTIFACTS_TO_BUILD="installer portable archive $ARTIFACTS_TO_BUILD"
             test "$ARCHITECTURE" = aarch64 || ARTIFACTS_TO_BUILD="$ARTIFACTS_TO_BUILD mingit-busybox"
             test "$ARCHITECTURE" != x86_64 || ARTIFACTS_TO_BUILD="$ARTIFACTS_TO_BUILD nuget"
           }