HDDS-13664. Persist pendingDeleteBytes only when feature is finalized.

[priyeshkaratha]

What changes were proposed in this pull request?

This PR introduces refactors the pending deletion metadata handling logic and comprehensive integration testing for the DataNode data distribution feature upgrade scenario.
The changes include:

1. Code Refactoring: Refactored to improve the pending deletion metadata handling: KeyValueContainerUtil.java
   • Extracted populatePendingDeletionMetadata() method for better separation of concerns
   • Added separate handler methods for different upgrade states
   • Enhanced the conditional logic to properly handle DATA_DISTRIBUTION feature finalization
   • Improved code readability and maintainability
2. Integration Test Addition: Created with comprehensive test coverage for the DN data distribution upgrade scenario, specifically validating: TestDNDataDistributionFinalization.java
   • Pre-finalization behavior (handlePreDataDistributionFeature path)
   • Post-finalization behavior (handlePostDataDistributionFeature path)
   • Missing metadata recalculation scenario (getAggregatePendingDelete path)

What is the link to the Apache JIRA

HDDS-13664

How was this patch tested?

Tested using integration added integration tests.

[ChenSammi]

Thanks @priyeshkaratha .