[improve][broker] Support shrink for ConcurrentSortedLongPairSet

[Technoboy-]

Motivation

Sometimes the messages sent to consumers are delayed over 100ms and we find that the CPU is wasted on :

"BookKeeperClientWorker-OrderedExecutor-4-0" #64 prio=5 os_prio=0 cpu=12748552.31ms elapsed=42037.79s tid=0x00007f7b4dc05720 nid=0xaf runnable  [0x00007f7a376f4000]
   java.lang.Thread.State: RUNNABLE
	at org.apache.pulsar.common.util.collections.ConcurrentLongPairSet.forEach(ConcurrentLongPairSet.java:157)
	at org.apache.pulsar.common.util.collections.ConcurrentSortedLongPairSet.items(ConcurrentSortedLongPairSet.java:136)
	at org.apache.pulsar.common.util.collections.ConcurrentSortedLongPairSet.items(ConcurrentSortedLongPairSet.java:128)
	at org.apache.pulsar.common.util.collections.ConcurrentSortedLongPairSet.items(ConcurrentSortedLongPairSet.java:113)
	at org.apache.pulsar.broker.service.persistent.MessageRedeliveryController.getMessagesToReplayNow(MessageRedeliveryController.java:109)
	at 

Then we find there are many empty datas in the map from dump :

ConcurrentSortedLongPairSet implements based on ConcurrentLongPairSet, and ConcurrentLongPairSet supports shrink, so support shrink for ConcurrentSortedLongPairSet to avoid iterator the empty data.

But the original removeIf has a bug if autoShrink=true, because when iterator the section, the internal table may change after remove, so result in some data not removed.

Reproduce Test:

LongPairSet set = new ConcurrentSortedLongPairSet(128, 2, true);
set.add(2, 2);
set.add(1, 3);
set.add(3, 1);
set.add(2, 1);
set.add(3, 2);
set.add(1, 2);
set.add(1, 1);
int removeItems = set.removeIf((ledgerId, entryId) -> {
    return ComparisonChain.start().compare(ledgerId, 1).compare(entryId, 3)
                    .result() <= 0;
 });
assertEquals(removeItems, 3);   // Will fail, removeItems = 2, (1,1) is not removed.

Modification

• Fix removeIf and add related test.

Documentation

• no-need-doc
  (Please explain why)

[codelipenghui]

/pulsarbot run-failure-checks

[gaoran10]

LGTM, left a trivial comment.

[shibd]

LGTM