Revert "Fix oslo-config value substitution"

This reverts commit 2405d366ba00c1559014e2f00f68387d6b5646ab.

Reason for revert: Incorrect reason for doing this patch was provided by me. 
Old version of oslo.config made collision.

Change-Id: I71e2fd55cdbe3ecf68672da9bfa270caf4f80fce
diff --git a/tcp_tests/helpers/oslo_cfg_types.py b/tcp_tests/helpers/oslo_cfg_types.py
index f7be2d7..aff8db0 100644
--- a/tcp_tests/helpers/oslo_cfg_types.py
+++ b/tcp_tests/helpers/oslo_cfg_types.py
@@ -133,5 +133,5 @@
         res = super(Cfg, self)._get_from_namespace(namespace, group_name)
         # Use the value from enviroment variable instead of config
         if hasattr(self, 'environment_value'):
-            res = self.environment_value
+            res = (self.environment_value, res[1])
         return res