test: Add functional test for Coinstats index

test/functional/test_framework/test_framework.py

@@ -757,7 +757,7 @@ class BitcoinTestFramework(metaclass=BitcoinTestMetaClass):
 
             os.rmdir(cache_path('wallets'))  # Remove empty wallets dir
             for entry in os.listdir(cache_path()):
-                if entry not in ['chainstate', 'blocks']:  # Only keep chainstate and blocks folder
+                if entry not in ['chainstate', 'blocks', 'indexes']:  # Only indexes, chainstate and blocks folders
                     os.remove(cache_path(entry))
 
         for i in range(self.num_nodes):