fix: default max_open_trades to inf instead of -1

Without this, the auto-conversion doesn't backpopulate to the config

closes #11752

freqtrade/configuration/config_validation.py

@@ -104,7 +104,7 @@ def _validate_unlimited_amount(conf: dict[str, Any]) -> None:
     """
     if (
         not conf.get("edge", {}).get("enabled")
-        and conf.get("max_open_trades") == float("inf")
+        and (conf.get("max_open_trades") == float("inf") or conf.get("max_open_trades") == -1)
         and conf.get("stake_amount") == UNLIMITED_STAKE_AMOUNT
     ):
         raise ConfigurationError("`max_open_trades` and `stake_amount` cannot both be unlimited.")

freqtrade/resolvers/strategy_resolver.py

@@ -79,7 +79,7 @@ class StrategyResolver(IResolver):
             ("ignore_buying_expired_candle_after", 0),
             ("position_adjustment_enable", False),
             ("max_entry_position_adjustment", -1),
-            ("max_open_trades", -1),
+            ("max_open_trades", float("inf")),
         ]
         for attribute, default in attributes:
             StrategyResolver._override_attribute_helper(strategy, config, attribute, default)