crostini: Mark all scarlet models as stable

All recent failures on dru and dumo were on informational tests, or
due to non-board-specific issues such as bug 1199870.

BUG=chromium:1059077
TEST=CQ

Change-Id: Ib090f4c5e7fc1c50dfa47159bab29920e7e56b71
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/tast-tests/+/2845537
Commit-Queue: Fergus Dall <sidereal@google.com>
Commit-Queue: Matthew Warton <mwarton@google.com>
Tested-by: Fergus Dall <sidereal@google.com>
Auto-Submit: Fergus Dall <sidereal@google.com>
Reviewed-by: Matthew Warton <mwarton@google.com>
diff --git a/src/chromiumos/tast/local/crostini/pre.go b/src/chromiumos/tast/local/crostini/pre.go
index 8fb086e..13dfc36 100644
--- a/src/chromiumos/tast/local/crostini/pre.go
+++ b/src/chromiumos/tast/local/crostini/pre.go
@@ -98,9 +98,6 @@
 	"electro",
 	// Platform sarien
 	"arcada",
-	// Platform scarlet
-	"dru",
-	"dumo",
 	// Platform samus
 	"samus", // crbug.com/1072877
 	// Platform stratego