Refactor: Replace explicit type arguments with diamond operator wherever possible across the project

[Akshat-Jain]

Description

As pointed out in this review comment, since we aren't supporting Java 8 anymore, we can switch to diamond operators wherever possible without specifying explicit type arguments.

Examples:

// Example 1:
private ArrayList<InputRow> longRows = new ArrayList<InputRow>();
// The above can be replaced with the following:
private ArrayList<InputRow> longRows = new ArrayList<>();

// Example 2:
new TypeReference<List<DataSegmentChangeRequest>>()
      {
      };
// The above can be replaced with the following:
new TypeReference<>() {};

This PR makes this change across the project.

Note: This change was done with IntelliJ's project-wide inspection results for warnings like Explicit type argument Integer, Iterator<Integer> can be replaced with <> . With that, there were a few compilation issues, which were manually fixed.

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This PR has:

• been self-reviewed.
  • using the concurrency checklist (Remove this item if the PR doesn't have any relation to concurrency.)
• 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.