Refactor custom checks with DescribeTopicPartitionsResponseAssertion

[ryan-gang]

This pull request introduces a new assertion type and refactors existing tests to use this new assertion for Kafka topic partition responses. The most important changes include the addition of the DescribeTopicPartitionsResponseAssertion type, updates to existing test functions to use this new assertion, and the addition of a new test function.

New Assertion Type:

• internal/assertions/describe_topic_assertion.go: Added DescribeTopicPartitionsResponseAssertion type for validating Kafka topic partition responses.

Refactoring Existing Tests:

• internal/stagep2.go: Updated the testDTPartitionWithUnknownTopic function to use DescribeTopicPartitionsResponseAssertion for response validation. [1] [2] [3]
• internal/stagep3.go: Updated the testDTPartitionWithTopicAndSinglePartition function to use DescribeTopicPartitionsResponseAssertion for response validation. [1] [2] [3]

New Test Function:

• internal/stagep4.go: Added a new test function testDTPartitionWithTopicAndMultiplePartitions2 to validate responses for topics with multiple partitions using the new assertion type.

Minor Refactor:

• internal/stagep5.go: Renamed the test function to testDTPartitionWithTopics and removed redundant error handling for GenerateLogDirs. [1] [2]