[stableversion] [autotest] remove the ability to update stable versions through django model

BUG=chromium:930793
TEST=None
Change-Id: Ie475099c3f1b46afa1c2a74ed8f3a4ce15102bf0
Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/third_party/autotest/+/1923228
Reviewed-by: Xixuan Wu <xixuan@chromium.org>
Tested-by: Gregory Nisbet <gregorynisbet@google.com>
diff --git a/server/frontend.py b/server/frontend.py
index 5f36cad..fe942e0 100644
--- a/server/frontend.py
+++ b/server/frontend.py
@@ -241,8 +241,7 @@
         @param board    The board to be updated.
         @param version  The new version to be assigned to the board.
         """
-        self._afe.run('set_stable_version',
-                      version=version, board=board)
+        raise RuntimeError("server.frontend._StableVersionMap::set_version is intentionally deleted")
 
 
     def delete_version(self, board):
@@ -254,7 +253,7 @@
 
         @param board    The board to be updated.
         """
-        self._afe.run('delete_stable_version', board=board)
+        raise RuntimeError("server.frontend._StableVersionMap::delete_version is intentionally deleted")
 
 
 class _OSVersionMap(_StableVersionMap):