Store erc20 loaded addresses in cache

- In ERC20Indexer, every chunk of addresses store them in cache
- It should not take any time, and in case task is interrupted during address loading it will be very useful, as loading can be restarted from that point

safe_transaction_service/history/indexers/erc20_events_indexer.py

@@ -279,13 +279,17 @@ def get_almost_updated_addresses(
         500k sounds like a good compromise memory/speed wise
         """
         created: Optional[datetime.datetime] = None
-        for created, address in (
+        for i, (created, address) in enumerate(
             query.values_list("created", "address")
             .order_by("created")
             .iterator(chunk_size=self.eth_erc20_load_addresses_chunk_size)
         ):
             addresses.add(address)
 
+            # Store addresses in cache every chunk, just in case task is interrupted during address loading
+            if i % self.eth_erc20_load_addresses_chunk_size == 0:
+                self.addresses_cache = AddressesCache(addresses, created)
+
         if created:
             last_checked = created