ISSUE-14073: Key shared subscription: hash ranges are not fully reported in stats

[sijie]

Original Issue: apache/pulsar#14073

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Describe the bug When I run pulsar-admin topics stats TOPIC-NAME and I have a KeyShared subscription with stickyHashRanges, with many ranges, the stats are not fully reporting the ranges, it looks like that for each consumer they report only the last set of ranges assigned to each Consumer and for some Consumers the list is empty even if the Consumer set the range and it is actually consuming messages.

There should be some bug here: https://github.com/apache/pulsar/blob/9abd6d30f39f74e255cd5dac40b77af3dce5c468/pulsar-broker/src/main/java/org/apache/pulsar/broker/service/HashRangeExclusiveStickyKeyConsumerSelector.java#L69

 public Map<Consumer, List<Range>> getConsumerKeyHashRanges() {
        Map<Consumer, List<Range>> result = new HashMap<>();
        Map.Entry<Integer, Consumer> prev = null;
        for (Map.Entry<Integer, Consumer> entry: rangeMap.entrySet()) {
            if (prev == null) {
                prev = entry;
            } else {
                if (prev.getValue().equals(entry.getValue())) {
                    result.computeIfAbsent(entry.getValue(), key -> new ArrayList<>())
                            .add(Range.of(prev.getKey(), entry.getKey()));
                }
                prev = null;
            }
        }
        return result;
    }

Additional context Pulsar 2.8.2

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