CI: downgrade docker/setup-buildx-action (#8062)

## Problem

I've bumped `docker/setup-buildx-action` in #8042 because I wasn't able
to reproduce the issue from #7445.
But now the issue appears again in
https://github.com/neondatabase/neon/actions/runs/9514373620/job/26226626923?pr=8059
The steps to reproduce aren't clear, it required
`docker/setup-buildx-action@v3` and rebuilding the image without cache,
probably

## Summary of changes
- Downgrade `docker/setup-buildx-action@v3` 
to `docker/setup-buildx-action@v2`

.github/workflows/build-build-tools-image.yml

@@ -64,7 +64,7 @@ jobs:
           mkdir -p /tmp/.docker-custom
           echo DOCKER_CONFIG=/tmp/.docker-custom >> $GITHUB_ENV
 
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@v2
 
       - uses: docker/login-action@v2
         with:

.github/workflows/build_and_test.yml

@@ -744,7 +744,7 @@ jobs:
         run: |
           mkdir -p .docker-custom
           echo DOCKER_CONFIG=$(pwd)/.docker-custom >> $GITHUB_ENV
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@v2
 
       - uses: docker/login-action@v3
         with:
@@ -822,11 +822,11 @@ jobs:
         run: |
           mkdir -p .docker-custom
           echo DOCKER_CONFIG=$(pwd)/.docker-custom >> $GITHUB_ENV
-      - uses: docker/setup-buildx-action@v3
+      - uses: docker/setup-buildx-action@v2
         with:
           # Disable parallelism for docker buildkit.
           # As we already build everything with `make -j$(nproc)`, running it in additional level of parallelisam blows up the Runner.
-          buildkitd-config-inline: |
+          config-inline: |
             [worker.oci]
               max-parallelism = 1