Drop v23.12 (EOL)

.ci/generate_page.sh

@@ -2,7 +2,6 @@
 
 export BRANCHES="
 	master
-	v23.12
 	v24.06
 	"
 

.gitlab-ci.yml

@@ -46,18 +46,6 @@ upstream-compat-master:
     - "*.check-passed"
     expire_in: 1 week
 
-upstream-compat-v23.12:
-  stage: check
-  <<: *only-default
-  allow_failure: true
-  script:
-  - ./test_upstream_compat_setup.sh "v23.12"
-  artifacts:
-    when: always
-    paths:
-      - "*.check-passed"
-    expire_in: 1 week
-
 upstream-compat-v24.06:
   stage: check
   <<: *only-default