Fix flaky tests org.apache.helix.rest.server.TestResourceAssignmentOptimizerAccessor(#2640)

[hofi1]

Issues

• My PR addresses the following Helix issues and references them in the PR description:

Fixes #2640

Description

The problem in this test is, that a json string gets directly asserted. JSON strings are equal, if they have the same content and structure. Not only the elements in the arrays can change, but also the elements in the same object can change location. This is not considered in the assertion and leads to a flaky test.

This problem was found by the NonDex Engine – to reproduce run

mvn -pl helix-rest edu.illinois:nondex-maven-plugin:2.1.1:nondex -Dtest=org.apache.helix.rest.server.TestResourceAssignmentOptimizerAccessor#testComputePartitionAssignment

Tests

No test have been written – one existing test has been updated.

• The following is the result of the "mvn test" command on the appropriate module:
  [INFO] ------------------------------------------------------------------------
  [INFO] BUILD SUCCESS
  [INFO] ------------------------------------------------------------------------
  [INFO] Total time: 02:53 min
  [INFO] Finished at: 2023-10-04T18:42:54-05:00