Benchmarking for wwctl overlay build

- Benchmarks overlay build in an environment with 1000 nodes
- Updates testenv to support both benchmarks and tests

To execute:

```
go test github.com/warewulf/warewulf/internal/app/wwctl/overlay/build -bench Benchmark_Overlay_Build
```

Signed-off-by: Jonathon Anderson <janderson@ciq.com>

internal/pkg/upgrade/node_test.go

@@ -775,10 +775,10 @@ func Test_UpgradeNodesYaml(t *testing.T) {
 	for _, tt := range nodesYamlUpgradeTests {
 		t.Run(tt.name, func(t *testing.T) {
 			env := testenv.New(t)
-			defer env.RemoveAll(t)
+			defer env.RemoveAll()
 			if tt.files != nil {
 				for fileName, content := range tt.files {
-					env.WriteFile(t, fileName, content)
+					env.WriteFile(fileName, content)
 				}
 			}
 			legacy, err := ParseNodes([]byte(tt.legacyYaml))