changelog: remove confusing double changelog

The essence is fix of a http client bug, libcurl bump is mere a method.

NO_DOC=changelog
NO_TEST=changelog
NO_CHANGELOG=changelog

changelogs/unreleased/bump-libcurl-to-8.3.0.md

-## feature/build
-
-* Updated libcurl to version 8.3.0.

changelogs/unreleased/gh-9086-fix-streaming-connection-stuck.md

-## bugfix/http
+## bugfix/lua/http client
 
 * Fixed a streaming connection stuck if etcd is stopped
   unexpectedly (gh-9086).