cros: Mark IDS_ASH_SHOW_WEBUI_LOGIN_BUTTON as non-translateable.

Bug: b/77862620
Change-Id: I780dde73b2cad048c9e2ca2e768113979bface16
Reviewed-on: https://chromium-review.googlesource.com/1015841Reviewed-by: Achuith Bhandarkar <achuith@chromium.org>
Commit-Queue: Jacob Dufault <jdufault@chromium.org>
Cr-Commit-Position: refs/heads/master@{#552116}

ash/ash_strings.grd

@@ -183,7 +183,7 @@ This file contains the strings for ash.
       <message name="IDS_ASH_ADD_USER_BUTTON" desc="Text shown on an add user button on login/locker screen">
         Add Person
       </message>
-      <message name="IDS_ASH_SHOW_WEBUI_LOGIN_BUTTON" desc="Button on login/lock screen which reverts to the previous implementation.">
+      <message name="IDS_ASH_SHOW_WEBUI_LOGIN_BUTTON" desc="Button on login/lock screen which reverts to the previous implementation." translateable="false">
         (TEMP) Show webui login; if used file bug (crbug.com) or feedback (alt+shift+i)
       </message>