HDDS-15806. Replace Thread.sleep with GenericTestUtils.waitFor in server-scm node tests

[smengcl]

What changes were proposed in this pull request?

1. Replaces fixed Thread.sleep waits with GenericTestUtils.waitFor polling in hadoop-hdds/server-scm node tests.
2. Fixed reversed assertEquals(actual, expected) argument order
3. testScmHeartbeat: the previous wait condition is satisfied at registration time, so it never actually depended on heartbeat processing. It now asserts NumHBProcessed, which is the signal that reflects processed heartbeats. And since processHeartbeat() runs synchronously in the test loop, this is a plain assertion with no wait

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-15806

How was this patch tested?

• Tests themselves.

[Copilot]

Pull request overview

This PR updates SCM node-related unit tests in hadoop-hdds/server-scm to avoid fixed-duration sleeps and instead wait deterministically for expected conditions using GenericTestUtils.waitFor, reducing test flakiness and unnecessary delays.

Changes:

• Replaced Thread.sleep(...) / static sleep(...) calls with GenericTestUtils.waitFor(...) polling in several SCM node tests.
• Updated test method signatures to declare TimeoutException where required by waitFor.
• Added the necessary test utility imports in the updated test classes.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
hadoop-hdds/server-scm/src/test/java/org/apache/hadoop/hdds/scm/node/TestSCMNodeMetrics.java	Replaces a fixed sleep after processing a heartbeat with a waitFor on healthy node count.
hadoop-hdds/server-scm/src/test/java/org/apache/hadoop/hdds/scm/node/TestSCMNodeManager.java	Replaces multiple fixed sleeps with waitFor conditions and updates thrown exceptions accordingly.
hadoop-hdds/server-scm/src/test/java/org/apache/hadoop/hdds/scm/node/TestContainerPlacement.java	Replaces a fixed sleep with waitFor to ensure node health state is reflected before asserting placement metrics.

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[sarvekshayr]

Thanks @smengcl for the patch.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

[Copilot]

Pull request overview

Copilot reviewed 3 out of 3 changed files in this pull request and generated 2 comments.

[Copilot]

Pull request overview

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