[Autofill Assistant] Consolidating server and client

This adds the non-implemented (or deprecated) actions from
the backend to the list of reserved fields.

Bug: none
Change-Id: Id77bffb0da81c2d17362cf7a0e383fa810250528
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2440669
Commit-Queue: Sandro Maggi <sandromaggi@google.com>
Auto-Submit: Sandro Maggi <sandromaggi@google.com>
Reviewed-by: Clemens Arbesser <arbesser@google.com>
Cr-Commit-Position: refs/heads/master@{#812712}

components/autofill_assistant/browser/service.proto

@@ -520,7 +520,7 @@ message ActionProto {
   // action sent to the client after this one. Default is false.
   optional bool clean_contextual_ui = 33;
 
-  reserved 34, 46, 47, 48, 50, 51;
+  reserved 8, 13 to 17, 20 to 23, 25 to 27, 30, 34, 38, 46 to 48, 50, 51;
 }
 
 // Result of |CollectUserDataProto| to be sent to the server.