Handle memory leaks from Mockito inline mocks

[Akshat-Jain]

Description

In #17056, we increased the test JVM max heap from 2 GB to 2.5 GB as we were running into OOM issues in some tests. It was a temporary measure to unblock the CI/CD pipeline.

On digging into the heap dump, the issue seems similar to mockito/mockito#2503, and the suggestion was to use Mockito.framework().clearInlineMocks().

This PR adds Mockito.framework().clearInlineMocks() to MSQTestBase#AfterEach to handle the memory leaks from Mockito's inline mocks, and reduces the test JVM max heap back to 2 GB.

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This PR has:

• been self-reviewed.
• added documentation for new or modified features or behaviors.
• a release note entry in the PR description.
• added Javadocs for most classes and all non-trivial methods. Linked related entities via Javadoc links.
• added or updated version, license, or notice information in licenses.yaml
• added comments explaining the "why" and the intent of the code wherever would not be obvious for an unfamiliar reader.
• added unit tests or modified existing tests to cover new code paths, ensuring the threshold for code coverage is met.
• added integration tests.
• been tested in a test Druid cluster.

[kgyrtkirk]

I don't think this leak-like usage is msq specific ; it could possibly be added to CalciteTestBase so that all Calcite*Test excercise this call