Create a custom ContainerManager for purging the TTL based znodes

[LZD-PratyushBhatt]

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This PR fixes #3036 TTL Znode doesn't expire in Test envs

Description

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The issue is related to ZooKeeper's TTL (Time-To-Live) node functionality and specifically how it behaves in the embedded ZooKeeper environment used in tests.

In a normal ZooKeeper deployment, a background ContainerManager thread runs periodically to clean up expired TTL nodes. However, in the embedded ZooKeeper used for testing, this background thread doesn't appear to be functioning properly. The ContainerManager is designed to run on a configurable schedule (default is 60 seconds), but in the test environment, this cleanup process doesn't happen.

The way we solve it is by creating a custom ContainerManager and using a fakeElapsedTimer.

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Code Quality

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[junkaixue]

This is a good start of the work! Make sure not breaking the test. But happy to see the tests to be stablized later.

[LZD-PratyushBhatt]

This is a good start of the work! Make sure not breaking the test. But happy to see the tests to be stablized later.

Hi @junkaixue , fixed the test issues, triggered CI through my fork, it seems to be passing now: https://github.com/LZD-PratyushBhatt/helix/actions/runs/15034195323/job/42252802394?pr=1

[junkaixue]

Are you using Helix style to format it? It looked wired. For the place you touched, we should fix it. Maybe it was not handled before.

[LZD-PratyushBhatt]

Hi @junkaixue , What do we mean by "helix style" here? I had earlier formatted the method in same way just as the getZkClient method above this.

[junkaixue]

This function has been repeated. Better make it as Util or in base class.

[LZD-PratyushBhatt]

One is in helix-core module and other is in zookeeper-api. And in zookeeper-api I dont see any packaging of test classes being done. So if we make this common then we will need to modify pom.xml in some places.