[qa] create_cache: Delete temp dir when done

Author: MarcoFalke

qa/rpc-tests/create_cache.py

@@ -12,9 +12,15 @@
 
 class CreateCache(BitcoinTestFramework):
 
+    def __init__(self):
+        super().__init__()
+
+        # Test network and test nodes are not required:
+        self.num_nodes = 0
+        self.nodes = []
+
     def setup_network(self):
-        # Don't setup any test nodes
-        self.options.noshutdown = True
+        pass
 
     def run_test(self):
         pass