Switch to toybox tar.

Test: treehugger
Change-Id: I4c561186c14cc44782a9e5c83d4d9c002addb3f6
diff --git a/ui/build/paths/config.go b/ui/build/paths/config.go
index c9946e2..7628fef 100644
--- a/ui/build/paths/config.go
+++ b/ui/build/paths/config.go
@@ -102,7 +102,6 @@
 	"realpath": Allowed,
 	"rsync":    Allowed,
 	"sh":       Allowed,
-	"tar":      Allowed,
 	"tr":       Allowed,
 	"unzip":    Allowed,
 	"zip":      Allowed,
@@ -164,6 +163,7 @@
 	"sort":      LinuxOnlyPrebuilt,
 	"stat":      LinuxOnlyPrebuilt,
 	"tail":      LinuxOnlyPrebuilt,
+	"tar":       LinuxOnlyPrebuilt,
 	"tee":       LinuxOnlyPrebuilt,
 	"timeout":   LinuxOnlyPrebuilt,
 	"touch":     LinuxOnlyPrebuilt,