[TrivialFix] Replace 'assertTrue(a in b)' with 'assertIn(a, b)'

Change-Id: I353acdd43def29f5c419ec5d551955133d3ce4e0
diff --git a/tempest/api/orchestration/stacks/test_nova_keypair_resources.py b/tempest/api/orchestration/stacks/test_nova_keypair_resources.py
index 8d12e75..160bf6f 100644
--- a/tempest/api/orchestration/stacks/test_nova_keypair_resources.py
+++ b/tempest/api/orchestration/stacks/test_nova_keypair_resources.py
@@ -78,10 +78,10 @@
         self.assertIn('-----BEGIN', output_map['KeyPair_PrivateKey'])
         # Test that second key generated public key, and private key is not
         # in the output due to save_private_key = false
-        self.assertTrue('KeyPairDontSavePrivate_PublicKey' in output_map)
-        self.assertTrue('Generated' in
-                        output_map['KeyPairDontSavePrivate_PublicKey'])
-        self.assertTrue(u'KeyPairDontSavePrivate_PrivateKey' in output_map)
+        self.assertIn('KeyPairDontSavePrivate_PublicKey', output_map)
+        self.assertIn('Generated',
+                      output_map['KeyPairDontSavePrivate_PublicKey'])
+        self.assertIn(u'KeyPairDontSavePrivate_PrivateKey', output_map)
         private_key = output_map['KeyPairDontSavePrivate_PrivateKey']
         self.assertTrue(len(private_key) == 0)