wwctl upgrade nodes --replace-overlays avoids applying overlays multiple times

- Closes: #1823

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

internal/pkg/upgrade/slices.go

@@ -15,3 +15,26 @@ func replaceSliceElement[T any](original []T, index int, replacement []T) []T {
 	}
 	return append(original[:index], append(replacement, original[index+1:]...)...)
 }
+
+func replaceOverlay(originals []string, toReplace string, replacements []string) []string {
+	if indexOf(originals, toReplace) == -1 {
+		return originals
+	}
+
+	lookup := make(map[string]bool)
+	for _, v := range originals {
+		lookup[v] = true
+	}
+
+	var newReplacements []string
+	for _, v := range replacements {
+		if !lookup[v] || v == toReplace {
+			newReplacements = append(newReplacements, v)
+		}
+	}
+
+	return replaceSliceElement(
+		originals,
+		indexOf(originals, toReplace),
+		newReplacements)
+}