Optimize tx processing RAM

- Don't load blob fields that are not used
- Process a smaller batch of transactions every time

For example, we detected a Safe in production with 782KB used by `logs` and other fields for every row:
- Before: 5000 × 782KB = 3.9GB
- After: 500 × 782KB = 391MB

Not even counting on the optimization not loading blob fields.

Author: Uxio0

config/settings/base.py

@@ -571,7 +571,7 @@
     "ETH_INTERNAL_TRACE_TXS_BATCH_SIZE", default=0
 )  # Number of `trace_transaction` calls allowed in the same RPC batch call, as results can be quite big
 ETH_INTERNAL_TX_DECODED_PROCESS_BATCH = env.int(
-    "ETH_INTERNAL_TX_DECODED_PROCESS_BATCH", default=5000
+    "ETH_INTERNAL_TX_DECODED_PROCESS_BATCH", default=500
 )  # Number of InternalTxDecoded to process together. Keep it low to be memory friendly
 
 # Event indexing configuration (L2 and ERC20/721)

safe_transaction_service/history/models.py

@@ -1325,7 +1325,14 @@ def pending_for_safes(self):
         return (
             self.not_processed()
             .order_by_processing_queue()
-            .select_related("internal_tx", "internal_tx__ethereum_tx")
+            .select_related("internal_tx__ethereum_tx")
+            # Defer large blob fields not used during processing to reduce memory usage
+            .defer(
+                "internal_tx__data",
+                "internal_tx__code",
+                "internal_tx__output",
+                "internal_tx__ethereum_tx__data",
+            )
         )
 
     def pending_for_safe(self, safe_address: ChecksumAddress):