Improve fetch_changelogs.py for major releases

For major releases we list the entries from all the various alpha releases and remove the one that were backported.

It's a very long work, a script could help .

added 14.0 stable Build System Doing labels

assigned to @pierov

marked this issue as related to #41272 (closed)

mentioned in merge request !1067 (merged)

removed Doing label

closed

marked this issue as related to #41263 (closed)