chore(release): sync changelog for v2.4.0 backports (#4200)

Updates CHANGELOG.md and removes news files for backports:
- #4199

Work towards #4175
Release-Tracking-Issue: #4175

Co-authored-by: github-actions[bot] <41898282+github-actions[bot]@users.noreply.github.com>

CHANGELOG.md

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 0c3e01c..f4f6847 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -43,6 +43,8 @@
   in favor of the format-agnostic `lockfiles` argument, which supports `uv.lock`.
 * (toolchain) Updated default Python 3.15 runtime from `3.15.0a8` to `3.15.0rc1`
   ([#4122](https://github.com/bazel-contrib/rules_python/pull/4122)).
+* (toolchain) Updated default Python 3.15 runtime from `3.15.0rc1` to
+  `3.15.0rc2`.
 * (toolchain) Updated the default Python toolchain version from `3.11` to `3.14`
   in {obj}`python.defaults`, {obj}`python_register_toolchains`, and
   {obj}`python_register_multi_toolchains`
@@ -105,6 +107,7 @@
   ([#4029](https://github.com/bazel-contrib/rules_python/issues/4029)).
 
 
+
 {#v2-3-4}
 ## [2.3.4] - 2026-09-21
 

news/update-cpython-3-15-rc2.changed.md

diff --git a/news/update-cpython-3-15-rc2.changed.md b/news/update-cpython-3-15-rc2.changed.md
deleted file mode 100644
index b0c9a52..0000000
--- a/news/update-cpython-3-15-rc2.changed.md
+++ /dev/null
@@ -1,2 +0,0 @@
-(toolchain) Updated default Python 3.15 runtime from `3.15.0rc1` to
-`3.15.0rc2`.