libct: remove deprecated MPOL_* constants

These were inadvertently added to our exported APIs by commit
eeda7bdf80cca ("Add memory policy support"). We couldn't remove them
from runc 1.4.x, but we deprecated them in commit 3741f9186d
("libct/configs: mark MPOL_* constants as deprecated") and marked them
for removal in runc 1.5. Users should never have used these in the first
place.

Signed-off-by: Aleksa Sarai <cyphar@cyphar.com>

CHANGELOG.md

@@ -27,7 +27,8 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
     - `libcontainer/configs.Thawed`
     - `libcontainer/configs.NewWeightDevice`
     - `libcontainer/configs.NewThrottleDevice`
-  - `libcontainer/configs.HookList.RunHooks` (#5141)
+  - `libcontainer/configs.HookList.RunHooks`. (#5141)
+  - `libcontainer/configs.MPOL_*` (#5414)
 
 ## [1.4.0] - 2025-11-27