ci: exit 75 on kafka port-open to guarantee retry on broker unreadiness

nc -z only verifies TCP connectivity, not that the Kafka broker is ready
to handle requests. Returning 0 on a successful nc -z check was a false
positive: the job would proceed, tests would fail with exit code 1, and
the exit_codes: 75 retry would never trigger.

Also add exit_codes: 75 to the PHP Language Tests explicit retry block,
which was overriding the default: retry from generate-common.php and
dropping the exit_codes condition.

Author: Leiyks

.gitlab/generate-common.php

@@ -104,6 +104,7 @@ function windows_git_setup_with_packages() {
   retry:
     max: 2
     when:
+      - script_failure
       - unknown_failure
       - data_integrity_failure
       - runner_system_failure

.gitlab/generate-tracer.php

@@ -518,6 +518,8 @@ function before_script_steps($with_docker_auth = false) {
       - api_failure
       - stuck_or_timeout_failure
       - job_execution_timeout
+    exit_codes:
+      - 75
   script:
     - make install_all
     - export XFAIL_LIST="dockerfiles/ci/xfail_tests/${PHP_MAJOR_MINOR}.list"

.gitlab/wait-for-service-ready.sh

@@ -51,11 +51,12 @@ wait_for_single_service() {
         fi
         ;;
       kafka)
-        # Kafka readiness via nc check + settle time
+        # nc -z only verifies TCP connectivity, not broker readiness.
+        # Exit 75 (EX_TEMPFAIL) to trigger CI retry instead of proceeding
+        # with a false-positive "ready" signal.
         if timeout 5 nc -z "${HOST}" "${PORT}" 2>/dev/null; then
-          sleep 5  # Additional settle time for Kafka
-          echo "Kafka is ready"
-          return 0
+          echo "Kafka port is open but broker readiness unverified; signalling retry"
+          exit 75
         fi
         ;;
       redis)