test: add a benchmark test for image pulls

[lucasrod16]

Describe what should be investigated or refactored

A benchmark test should be added for the PullAll() function

Links to any relevant code

https://github.com/defenseunicorns/zarf/blob/02389274c61b59385ac339d6d690a148878427f9/src/internal/packager/images/pull.go#L39

Additional context

This benchmark test will serve as a baseline for what we expect the performance of image pulls to be.

Example benchmark used to test #2409:

// SPDX-License-Identifier: Apache-2.0
// SPDX-FileCopyrightText: 2024-Present The Zarf Authors

// Package images provides functions for building and pushing images.
package images

import (
	"testing"

	"github.com/defenseunicorns/zarf/src/config"
	"github.com/defenseunicorns/zarf/src/pkg/transform"
)

// BenchmarkPullAll benchmarks the PullAll function.
func BenchmarkPullAll(b *testing.B) {
	config.CommonOptions.CachePath = b.TempDir()
	imageConfig := ImageConfig{
		ImagesPath: b.TempDir(),
		ImageList: []transform.Image{
			{
				Reference: "registry1.dso.mil/ironbank/fluxcd/source-controller:v1.2.4",
			},
			{
				Reference: "registry1.dso.mil/ironbank/fluxcd/kustomize-controller:v1.2.2",
			},
			{
				Reference: "registry1.dso.mil/ironbank/fluxcd/helm-controller:v0.37.4",
			},
			{
				Reference: "registry1.dso.mil/ironbank/fluxcd/notification-controller:v1.2.4",
			},
			{
				Reference: "registry1.dso.mil/ironbank/big-bang/base:2.1.0",
			},
			{
				Reference: "registry1.dso.mil/ironbank/twistlock/console/console:32.01.128",
			},
			{
				Reference: "registry1.dso.mil/ironbank/twistlock/defender/defender:32.01.128",
			},
		},
	}
	b.ResetTimer()
	for i := 0; i < b.N; i++ {
		_, err := imageConfig.PullAll()
		if err != nil {
			b.Fatalf("Error in PullAll: %v", err)
		}
	}
}

[Noxsios]

This benchmark should also cover cold vs warm caches

[lucasrod16]

In hindsight, this is likely a premature optimization. If we feel the need to measure the performance of image pulls with a benchmark test in the future, we can reopen this issue or create a new one.

See rules 1 and 2 in Rob Pike's 5 Rules of Programming:

https://users.ece.utexas.edu/~adnan/pike.html