The following ILM tests all contain switch statements with branches that will never execute. The tests use a `between(x, y)` switch expression, but there are `case` values that are outside the randomised range. We need to fix these before #88739 can be merged. By "fix", I mean either remove the spurious cases, or if we actually want them, then extend the randomized range.

   * ActionConfigStatsTests
   * AllocateActionTests
   * CopyExecutionStateStepTests
   * RolloverActionTests
   * WaitForRolloverReadyStepTests

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ilm/CopyExecutionStateStepTests.java
String shrunkIndexPrefix = randomAlphaOfLength(10);
        StepKey targetNextStepKey = randomStepKey();
        return new CopyExecutionStateStep(stepKey, nextStepKey, (index, state) -> shrunkIndexPrefix + index, targetNextStepKey);
    }
    @Override
    protected CopyExecutionStateStep mutateInstance(CopyExecutionStateStep instance) {
        StepKey key = instance.getKey();
        StepKey nextKey = instance.getNextStepKey();
        BiFunction<String, LifecycleExecutionState, String> indexNameSupplier = instance.getTargetIndexNameSupplier();
        StepKey targetNextStepKey = instance.getTargetNextStepKey();
        switch (between(0, 2)) {
            case 0 -> key = new StepKey(key.getPhase(), key.getAction(), key.getName() + randomAlphaOfLength(5));
            case 1 -> nextKey = new StepKey(key.getPhase(), key.getAction(), key.getName() + randomAlphaOfLength(5));
            case 2 -> indexNameSupplier = (index, state) -> randomAlphaOfLengthBetween(11, 15) + index;
            case 3 -> targetNextStepKey = new StepKey(
                targetNextStepKey.getPhase(),
                targetNextStepKey.getAction(),
                targetNextStepKey.getName() + randomAlphaOfLength(5)
            );
            default -> throw new AssertionError("Illegal randomisation branch");
        }
        return new CopyExecutionStateStep(key, nextKey, indexNameSupplier, targetNextStepKey);
    }
    @Override
    protected CopyExecutionStateStep copyInstance(CopyExecutionStateStep instance) {
        return new CopyExecutionStateStep(
            instance.getKey(),
            instance.getNextStepKey(),
            instance.getTargetIndexNameSupplier(),
            instance.getTargetNextStepKey()