Fix release notes templates (#6697)

* WIP

* Fix templates

- fix conditions to fetch misc PRs
- render the misc section only if required
- add html comment to help debugging
- add a new API section to T2 labels

polkadot/scripts/ci/changelog/templates/changes_runtime.md.tera

@@ -12,6 +12,8 @@
 
 {%- if pr.meta.T and pr.meta.T.value == 1 and not pr.title is containing("ompanion") %}
 - {{ m_c::change(c=pr) }}
+{%- else %}
+<!-- EXCLUDED PR#{{pr.number}} - {{pr.html_url}} -->
 {%- endif -%}
 {%- endif -%}