Remove deprecated skip decorators

This patch aims to remove 'skip_unless_config' and 'skip_if_config'
decorators, which marked as deprecated and would be removed in Queens.

Change-Id: I45a0216b7ab34e962b0f4802df77019b0c613d49
diff --git a/releasenotes/notes/remove-deprecated-skip-decorators-f8b42d812d20b537.yaml b/releasenotes/notes/remove-deprecated-skip-decorators-f8b42d812d20b537.yaml
new file mode 100644
index 0000000..920bc5d
--- /dev/null
+++ b/releasenotes/notes/remove-deprecated-skip-decorators-f8b42d812d20b537.yaml
@@ -0,0 +1,5 @@
+---
+upgrade:
+  - |
+    Remove two deprecated skip decorators in ``config`` module:
+    ``skip_unless_config`` and ``skip_if_config``.