Allow use of --strategy-list with freqai, with warning (#7455)

* Allow use of --strategy-list with freqai, with warning

* ensure populate_any_indicators is identical for resused identifiers

* use pair instead of metadata["pair"]

Co-authored-by: robcaulk <rob.caulk@gmail.com>

freqtrade/optimize/backtesting.py

@@ -91,8 +91,8 @@ class Backtesting:
 
         if self.config.get('strategy_list'):
             if self.config.get('freqai', {}).get('enabled', False):
-                raise OperationalException(
-                    "You can't use strategy_list and freqai at the same time.")
+                logger.warning("Using --strategy-list with FreqAI REQUIRES all strategies "
+                               "to have identical populate_any_indicators.")
             for strat in list(self.config['strategy_list']):
                 stratconf = deepcopy(self.config)
                 stratconf['strategy'] = strat