Remove obsolete ConsensusEnsurer

As a result of #1657 out-of-place parent blocks are marked as non-consensus
more reliably, i.e. they will eventually be fetched even if first attempt is
unsuccessful.

The `ConsensusEnsurer` module, on the contrary, only tried refetching block
once, and left it as-is if the refetch failed. Now it is not needed anymore.

apps/indexer/lib/indexer/block/realtime/consensus_ensurer.ex

@@ -1,34 +0,0 @@
-defmodule Indexer.Block.Realtime.ConsensusEnsurer do
-  @moduledoc """
-  Triggers a refetch if a given block doesn't have consensus.
-
-  """
-  require Logger
-
-  alias Explorer.Chain
-  alias Explorer.Chain.Hash
-  alias Indexer.Block.Realtime.Fetcher
-
-  def perform(_, number, _) when not is_integer(number) or number < 0, do: :ok
-
-  def perform(%Hash{byte_count: unquote(Hash.Full.byte_count())} = block_hash, number, block_fetcher) do
-    case Chain.hash_to_block(block_hash) do
-      {:ok, %{consensus: true} = _block} ->
-        :ignore
-
-      _ ->
-        Logger.info(fn ->
-          [
-            "refetch from consensus was found on block (",
-            to_string(number),
-            "). A reorg initiated."
-          ]
-        end)
-
-        # trigger refetch if consensus=false or block was not found
-        Fetcher.fetch_and_import_block(number, block_fetcher, true)
-    end
-
-    :ok
-  end
-end

apps/indexer/lib/indexer/block/realtime/fetcher.ex

@@ -27,7 +27,7 @@ defmodule Indexer.Block.Realtime.Fetcher do
   alias Explorer.Chain.TokenTransfer
   alias Explorer.Counters.AverageBlockTime
   alias Indexer.{AddressExtraction, Block, TokenBalances, Tracer}
-  alias Indexer.Block.Realtime.{ConsensusEnsurer, TaskSupervisor}
+  alias Indexer.Block.Realtime.TaskSupervisor
   alias Timex.Duration
 
   @behaviour Block.Fetcher
@@ -269,12 +269,7 @@ defmodule Indexer.Block.Realtime.Fetcher do
   @decorate span(tracer: Tracer)
   defp do_fetch_and_import_block(block_number_to_fetch, block_fetcher, retry) do
     case fetch_and_import_range(block_fetcher, block_number_to_fetch..block_number_to_fetch) do
-      {:ok, %{inserted: inserted, errors: []}} ->
-        for block <- Map.get(inserted, :blocks, []) do
-          args = [block.parent_hash, block.number - 1, block_fetcher]
-          Task.Supervisor.start_child(TaskSupervisor, ConsensusEnsurer, :perform, args)
-        end
-
+      {:ok, %{inserted: _, errors: []}} ->
         Logger.debug("Fetched and imported.")
 
       {:ok, %{inserted: _, errors: [_ | _] = errors}} ->