BB-727: Fix ZookeeperConfigManager event listener leaks

[BourgoisMickael]

• improve some logs
• warn early for event listener leaks
• avoid send a remove to zk when a watcher notify the removed bucket config
• separate list and get configs

Below a sequence diagram showing in red a few problems fixed here

[bert-e]

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[codecov]

Codecov Report

❌ Patch coverage is 84.61538% with 4 lines in your changes missing coverage. Please review.
✅ Project coverage is 74.04%. Comparing base (354107d) to head (694086a).

Files with missing lines	Patch %	Lines
...tification/configManager/ZookeeperConfigManager.js	84.61%	4 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
...ensions/notification/NotificationQueuePopulator.js	98.13% <ø> (ø)
lib/BackbeatConsumer.js	92.64% <ø> (+0.27%)	⬆️
...tification/configManager/ZookeeperConfigManager.js	83.16% <84.61%> (-0.35%)	⬇️

... and 3 files with indirect coverage changes

Components	Coverage Δ
Bucket Notification	80.30% <84.61%> (-0.04%)	⬇️
Core Library	80.32% <ø> (-0.56%)	⬇️
Ingestion	70.28% <ø> (ø)
Lifecycle	78.67% <ø> (ø)
Oplog Populator	85.06% <ø> (ø)
Replication	58.55% <ø> (-0.04%)	⬇️
Bucket Scanner	85.76% <ø> (ø)

@@                 Coverage Diff                 @@
##           development/9.0    #2687      +/-   ##
===================================================
- Coverage            74.27%   74.04%   -0.24%     
===================================================
  Files                  201      201              
  Lines                13444    13458      +14     
===================================================
- Hits                  9986     9965      -21     
- Misses                3448     3483      +35     
  Partials                10       10              

Flag	Coverage Δ
api:retry	9.45% <0.00%> (-0.02%)	⬇️
api:routes	9.26% <0.00%> (-0.01%)	⬇️
bucket-scanner	85.76% <ø> (ø)
ft_test:queuepopulator	8.91% <0.00%> (-1.30%)	⬇️
ingestion	12.51% <0.00%> (-0.02%)	⬇️
lib	7.47% <0.00%> (-0.01%)	⬇️
lifecycle	18.67% <0.00%> (-0.02%)	⬇️
notification	1.04% <0.00%> (-0.01%)	⬇️
replication	18.47% <0.00%> (-0.02%)	⬇️
unit	50.03% <84.61%> (+0.03%)	⬆️

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[Copilot]

Pull Request Overview

This PR addresses event listener leaks in the ZookeeperConfigManager by improving watcher management and separating list/get config operations. The key improvements include early detection of watcher leaks, preventing redundant ZooKeeper remove operations when watchers notify of deleted bucket configs, and enhanced logging for better debugging.

• Added early warning system for ZooKeeper watcher leaks to detect issues before hitting EventEmitter limits
• Separated getConfig and listConfigs event handlers to avoid unnecessary bucket list operations
• Modified removeConfig to optionally skip ZooKeeper emission when triggered by a watcher notification

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
lib/BackbeatConsumer.js	Enhanced logging to safely convert Buffer keys to strings for better debugging
extensions/notification/configManager/ZookeeperConfigManager.js	Core fixes for watcher leak detection, separated list/get config handlers, and added conditional ZK emission for removeConfig
extensions/notification/NotificationQueuePopulator.js	Corrected typo in comment from "deleter" to "deleted"

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