Go back to the host sed until we have a faster prebuilt.

Bug: https://issuetracker.google.com/131747477
Test: treehugger
Change-Id: I120fe1200216afdb492bd1353848d12a4be1f496
diff --git a/ui/build/paths/config.go b/ui/build/paths/config.go
index 54006d2..4a30391 100644
--- a/ui/build/paths/config.go
+++ b/ui/build/paths/config.go
@@ -102,6 +102,7 @@
 	"python3":  Allowed,
 	"realpath": Allowed,
 	"rsync":    Allowed,
+	"sed":      Allowed,
 	"sh":       Allowed,
 	"tar":      Allowed,
 	"timeout":  Allowed,
@@ -155,7 +156,6 @@
 	"readlink":  LinuxOnlyPrebuilt,
 	"rm":        LinuxOnlyPrebuilt,
 	"rmdir":     LinuxOnlyPrebuilt,
-	"sed":       LinuxOnlyPrebuilt,
 	"seq":       LinuxOnlyPrebuilt,
 	"setsid":    LinuxOnlyPrebuilt,
 	"sha1sum":   LinuxOnlyPrebuilt,