fix: flatten drifted changelog fragments

changelog.d/135.md

@@ -1,5 +1,3 @@
-### Fixed
-
 - `drills/README.md` no longer tells the builder to delete the scratch repo —
   a step no fleet identity can perform, because `delete_repo` is deliberately
   absent from bot tokens. The builder's end state is **archive**

changelog.d/137.md

@@ -1,5 +1,3 @@
-### Fixed
-
 - `blocker:unrequested` now clears the moment the panel is asked: the labels
   caller (and the `docs/CONSUMERS.md` stub) listens on `review_requested` and
   `review_request_removed`, so the one event that falsifies the label — or

changelog.d/144.md

@@ -1,5 +1,3 @@
-### Fixed
-
 - The `docs/CONSUMERS.md` labels-caller stub lists the same `issues:` types
   as ceremony's own caller — `edited` and `reopened` included — so a consumer
   adopting the stub wakes when an issue body's `Blocked by #N` declaration is

changelog.d/151.md

@@ -1,5 +1,3 @@
-### Changed
-
 - Doctrine names the second `Closes #N` exception: a same-repo PR whose
   authorizing issue marks an acceptance criterion post-merge uses `Refs #N`,
   and triage closes the issue by hand on the evidence — merging #143