Remove: Drop unused changelog dir including 22.4 changelog

The changelog is shown at the GitHub release pages and also can be
created automatically via the `pontos-changelog` tool. There is no need
to keep it in the git history.

changelog.toml

@@ -1,11 +1,9 @@
 commit_types = [
-    { message = "^add", group = "Added"},
-    { message = "^remove", group = "Removed"},
-    { message = "^change", group = "Changed"},
-    { message = "^fix", group = "Bug Fixes"},
-    { message = "^doc", group = "Documentation"},
-    { message = "^refactor", group = "Refactor"},
-    { message = "^test", group = "Testing"},
+    { message = "^add", group = "Added" },
+    { message = "^remove", group = "Removed" },
+    { message = "^change", group = "Changed" },
+    { message = "^fix", group = "Bug Fixes" },
+    { message = "^doc", group = "Documentation" },
+    { message = "^refactor", group = "Refactor" },
+    { message = "^test", group = "Testing" },
 ]
-
-changelog_dir = "changelog"