bzip2/xz: use the prebuilts.

We added the prebuilts a while ago, but forgot to clean this up.

Test: treehugger
Change-Id: I8920f0c9d77951332a663750102ceeabcb565970

ui/build/paths/config.go

@@ -76,7 +76,6 @@ func GetConfig(name string) PathConfig {
 var Configuration = map[string]PathConfig{
 	"bash":     Allowed,
 	"bc":       Allowed,
-	"bzip2":    Allowed,
 	"date":     Allowed,
 	"dd":       Allowed,
 	"diff":     Allowed,
@@ -104,7 +103,6 @@ var Configuration = map[string]PathConfig{
 	"timeout":  Allowed,
 	"tr":       Allowed,
 	"unzip":    Allowed,
-	"xz":       Allowed,
 	"zip":      Allowed,
 	"zipinfo":  Allowed,