test: use trap to remove cache volume

Signed-off-by: CrazyMax <crazy-max@users.noreply.github.com>

hack/test

@@ -36,10 +36,9 @@ cacheVolume="buildx-test-cache"
 if ! docker container inspect "$cacheVolume" >/dev/null 2>/dev/null; then
   docker create -v /root/.cache -v /root/.cache/registry -v /go/pkg/mod --name "$cacheVolume" alpine
 fi
+if [ "$TEST_KEEP_CACHE" != "1" ]; then
+  trap 'docker rm -v $cacheVolume' EXIT
+fi
 
 cid=$(docker create --rm -v /tmp $testReportsVol --volumes-from=$cacheVolume -e GITHUB_REF -e TEST_DOCKERD -e TEST_BUILDKIT_IMAGE -e SKIP_INTEGRATION_TESTS -e GOTESTSUM_FORMAT ${BUILDKIT_INTEGRATION_SNAPSHOTTER:+"-eBUILDKIT_INTEGRATION_SNAPSHOTTER"} -e BUILDKIT_REGISTRY_MIRROR_DIR=/root/.cache/registry --privileged $iid gotestsum $gotestsumArgs --packages="${TESTPKGS:-./...}" -- $gotestArgs ${TESTFLAGS:--v})
 docker start -a -i $cid
-
-if [ "$TEST_KEEP_CACHE" != "1" ]; then
-  docker rm -v $cacheVolume
-fi