Transforms can be configured to search incredibly broad index patterns. These cause the lower level actions used by transforms to iterate huge numbers of shards unless measures are taken to restrict which shards are considered using information available in cluster state.

Anywhere where transforms calls an action that iterates shards it must use the `index_filter` functionality of that action to reduce scope. Calls to be changed:

- [x] Field caps
- [x] Creating PIT readers - requires #99740 be implemented as a pre-requisite
x-pack/plugin/transform/src/main/java/org/elasticsearch/xpack/transform/transforms/ClientTransformIndexer.java
if (updated == false) {
            logger.warn(
                "[{}] Unexpected change to internal state detected, expected [{}], got [{}]",
                transformConfig.getId(),
                expectedValue,
                seqNoPrimaryTermAndIndexHolder.get()
            );
            assert updated : "[" + getJobId() + "] unexpected change to seqNoPrimaryTermAndIndex.";
        }
    }
    @Nullable
    SeqNoPrimaryTermAndIndex getSeqNoPrimaryTermAndIndex() {
        return seqNoPrimaryTermAndIndexHolder.get();
    }
    @Override
    protected void afterFinishOrFailure() {
        closePointInTime();
        super.afterFinishOrFailure();
    }
    @Override
    protected void onStop() {
        closePointInTime();
        super.onStop();
    }
    private void closePointInTime() {
        for (String name : namedPits.keySet()) {
            closePointInTime(name);
        }
    }
    private void closePointInTime(String name) {