ci(fix): Temporarily avoid specifying `provenance` (#3072)

* ci(fix): Temporarily avoid specifying `provenance`

As the test workflow does not use the `docker-container` buildx driver, it uses the Docker Engine bundled BuildKit version which until v23 release does not support attestations.

Likewise the current buildx version in CI is `0.10.0` which does not respect `--provenance false`, the presence of the option appears to trigger a BuildKit version compatibility check and fail early before it considers the value of the option.

* chore: Use buildx `docker-container` driver instead

An alternative solution to omitting `provenance: false` (_not supported by buildx 0.10.0 with default `docker` driver when Docker Engine bundles BuildKit less than 0.10.0, which is the case prior to the Docker Engine v23 release_). 

This approach provides more consistency with the build and publish workflows by using the same buildx `docker-container` driver (_and thus newer BuildKit, enabling support for  `provenance: false`_).

* chore: Revise test workflow inline docs

Buildx `docker-container` driver is not needed here, but it does seem like it improves cache-hit ratio when building from the retrieved build cache (from the earlier build workflow). Possibly due to building with the same BuildKit version.

.github/workflows/generic_test.yml

@@ -34,9 +34,14 @@ jobs:
           path: /tmp/.buildx-cache
           key: cache-buildx-${{ inputs.cache-key }}
 
+      # Configures buildx to use `docker-container` driver,
+      # Ensures consistent BuildKit version (not coupled to Docker Engine),
+      # and increased compatibility of the build cache vs mixing buildx drivers.
+      - name: 'Set up Docker Buildx'
+        uses: docker/setup-buildx-action@v2.4.0
+
       # Importing from the cache should create the image within approx 30 seconds:
-      # Earlier `buildx` + `qemu` steps are not needed as no cache is exported,
-      # and only a single platform (AMD64) is loaded:
+      # NOTE: `qemu` step is not needed as we only test for AMD64.
       - name: 'Build AMD64 image from cache'
         uses: docker/build-push-action@v4.0.0
         with: