Count the connection failure as the condition of quarantine

[zymap]

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Motivation

Currently, the bookie client quarantine mechanism primarily triggers based on read and write error responses from Bookies. However, in multi-region deployments, a common failure mode is the Network Partition or DNS Resolution Failure at the Region level.

In such scenarios:

1. A Bookie remains registered in ZooKeeper (it can still heartbeat to its local ZK observer).
2. The Client (Broker) cannot resolve the Bookie's IP or establish a TCP connection.
3. The EnsemblePlacementPolicy (especially RegionAwareEnsemblePlacementPolicy) sees the Bookie as "Available" and repeatedly selects it to satisfy minRack or E/Qw constraints.
4. The LedgerHandle fails to write because it cannot initialize a connection handle, triggering an Ensemble Change.
5. Because the connection failure didn't trigger a quarantine, the placement policy picks the same problematic Bookie again in the next iteration.

This creates an infinite Ensemble Change loop, causing the Ledger write to hang indefinitely and bloating the Ledger metadata in ZooKeeper with thousands of segments.

[lhotari]

suggesting a new name for the config. It seems that getBoolean would throw an exception if the setting is missing and when the default value isn't provided.