Revert "Switch to toybox cp(1)."

This reverts commit 9886695763.

Reason for revert: http://b/122623408
Bug: http://b/122623408

Change-Id: Ib9ec92f9dd6f9a0db7f598b10241b0474e46aba0

ui/build/paths/config.go

@@ -78,6 +78,7 @@ var Configuration = map[string]PathConfig{
 	"bash":      Allowed,
 	"bc":        Allowed,
 	"bzip2":     Allowed,
+	"cp":        Allowed,
 	"date":      Allowed,
 	"dd":        Allowed,
 	"diff":      Allowed,
@@ -154,7 +155,6 @@ var Configuration = map[string]PathConfig{
 	"chmod":    Toybox,
 	"cmp":      Toybox,
 	"comm":     Toybox,
-	"cp":       Toybox,
 	"cut":      Toybox,
 	"dirname":  Toybox,
 	"du":       Toybox,