Revert "Move sed(1) to toybox."

This reverts commit e259a66d12efa3122be2f34356ef04d7e223e453.

Reason for revert: http://b/122744241

Change-Id: Id0e86ab79df2356fe12a2659fe39d02469ed9280
diff --git a/ui/build/paths/config.go b/ui/build/paths/config.go
index d6f11b1..4dc62b8 100644
--- a/ui/build/paths/config.go
+++ b/ui/build/paths/config.go
@@ -113,6 +113,7 @@
 	"realpath":  Allowed,
 	"rm":        Allowed,
 	"rsync":     Allowed,
+	"sed":       Allowed,
 	"sh":        Allowed,
 	"sha1sum":   Allowed,
 	"sha256sum": Allowed,
@@ -165,7 +166,6 @@
 	"paste":    Toybox,
 	"pwd":      Toybox,
 	"rmdir":    Toybox,
-	"sed":      Toybox,
 	"setsid":   Toybox,
 	"sleep":    Toybox,
 	"tail":     Toybox,