Merged 2 tests dependent on each other

One created metadata, the other deleted them. They would fail if they would get
ran in a different order or individually.

I also refactored them a bit to do this.

Change-Id: I21a8ab9f077e742eb40ea29fcea5e04f9d7dd043
diff --git a/tempest/api/object_storage/test_account_services.py b/tempest/api/object_storage/test_account_services.py
index ddedfc6..7769617 100644
--- a/tempest/api/object_storage/test_account_services.py
+++ b/tempest/api/object_storage/test_account_services.py
@@ -53,27 +53,25 @@
         self.assertIn('x-account-bytes-used', resp)
 
     @attr(type='smoke')
-    def test_create_account_metadata(self):
+    def test_create_and_delete_account_metadata(self):
+        header = 'test-account-meta'
+        data = 'Meta!'
         # add metadata to account
-        metadata = {'test-account-meta': 'Meta!'}
-        resp, _ = \
-            self.account_client.create_account_metadata(metadata=metadata)
+        resp, _ = self.account_client.create_account_metadata(
+            metadata={header: data})
         self.assertEqual(resp['status'], '204')
 
-        resp, metadata = self.account_client.list_account_metadata()
-        self.assertIn('x-account-meta-test-account-meta', resp)
-        self.assertEqual(resp['x-account-meta-test-account-meta'], 'Meta!')
+        resp, _ = self.account_client.list_account_metadata()
+        self.assertIn('x-account-meta-' + header, resp)
+        self.assertEqual(resp['x-account-meta-' + header], data)
 
-    @attr(type='smoke')
-    def test_delete_account_metadata(self):
         # delete metadata from account
-        metadata = ['test-account-meta']
         resp, _ = \
-            self.account_client.delete_account_metadata(metadata=metadata)
+            self.account_client.delete_account_metadata(metadata=[header])
         self.assertEqual(resp['status'], '204')
 
-        resp, metadata = self.account_client.list_account_metadata()
-        self.assertNotIn('x-account-meta-test-account-meta', resp)
+        resp, _ = self.account_client.list_account_metadata()
+        self.assertNotIn('x-account-meta-' + header, resp)
 
     @attr(type='negative')
     def test_list_containers_with_non_authorized_user(self):