test: skip catalog client images that cannot execute on the host CPU (#12014)

New upstream releases build for x86-64-v3 (AVX2) - ClickHouse since
26.5, plus the DuckDB iceberg extension and pylance wheels - so on a
runner whose CPU lacks AVX2 the container dies on SIGILL before the
test reaches any SeaweedFS code. Probe each third-party image first
and skip on the illegal-instruction exit instead of failing; other
errors still surface normally.

test/testutil/helpers.go

@@ -2,12 +2,15 @@ package testutil
 
 import (
 	"context"
+	"errors"
 	"fmt"
 	"net"
 	"net/http"
 	"os"
 	"os/exec"
 	"path/filepath"
+	"strings"
+	"testing"
 	"time"
 )
 
@@ -20,6 +23,34 @@ func HasDocker() bool {
 	return cmd.Run() == nil
 }
 
+// RequireImageRunnable runs a throwaway container with the given `docker run`
+// arguments and skips the test when its process dies on SIGILL. Upstream
+// images increasingly target x86-64-v3 (AVX2) - ClickHouse since 26.5 - so a
+// host CPU without those instructions cannot run them at all, and the failure
+// says nothing about the code under test. Any other outcome, whether a clean
+// run, an ordinary non-zero exit, or a pull failure, is left for the test
+// itself to report: the probe can only skip on the one failure the code
+// cannot cause.
+func RequireImageRunnable(t *testing.T, args ...string) {
+	t.Helper()
+
+	ctx, cancel := context.WithTimeout(context.Background(), 2*time.Minute)
+	defer cancel()
+	cmd := exec.CommandContext(ctx, "docker", append([]string{"run", "--rm"}, args...)...)
+	out, err := cmd.CombinedOutput()
+	if err == nil {
+		return
+	}
+	var exitErr *exec.ExitError
+	// 132 = 128 + SIGILL: docker propagates the container process's death.
+	if errors.As(err, &exitErr) &&
+		(exitErr.ExitCode() == 132 ||
+			strings.Contains(string(out), "Illegal instruction")) {
+		t.Skipf("image cannot execute on this CPU (illegal instruction): docker run %s\n%s",
+			strings.Join(args, " "), out)
+	}
+}
+
 func FindBindIP() string {
 	addrs, err := net.InterfaceAddrs()
 	if err != nil {