[AMORO-4166] [Improvement]: Implement heap-based flush mechanism for SortedPosDeleteWriter to prevent OOM.

[slfan1989]

Why are the changes needed?

Close #4166.

SortedPosDeleteWriter currently only flushes buffered position deletes based on a record count threshold, which can cause OutOfMemoryError (OOM) in memory-constrained environments when processing large-scale delete operations.

There was a TODO comment in the code indicating the need for a heap memory-based flush policy:

// TODO Flush buffer based on the policy that checking whether whole heap memory size exceed the
// threshold.

This PR implements the heap-based flush mechanism to prevent OOM issues by monitoring JVM heap usage and triggering flush when memory pressure is detected, while maintaining backward compatibility.

Brief change log

Core Implementation:

• SortedPosDeleteWriter:
  • Added HeapUsageProvider interface to monitor JVM heap memory (max/used)
  • Implemented shouldFlushByHeap() method with safety guards (minimum records, valid ratio check)
  • Modified delete() logic to flush when records >= recordsNumThreshold || shouldFlushByHeap()
  • Added multiple constructor overloads to support new parameters while maintaining backward compatibility

Configuration:

• TableProperties: Added three new table properties:
  • pos-delete.flush.heap.ratio (default: 0.8) - Heap usage ratio threshold
  • pos-delete.flush.records (default: Long.MAX_VALUE) - Record count threshold
  • pos-delete.flush.heap.min-records (default: 1000) - Minimum records before heap flush

How was this patch tested?

• Add some test cases that check the changes thoroughly including negative and positive cases if possible
  • Added TestSortedPosDeleteWriterHeapFlush with mock HeapUsageProvider to test heap-based flush logic
  • Test case 1: Verify flush is triggered when heap usage exceeds threshold
  • Test case 2: Verify heap flush is disabled when ratio is set to 0

Documentation

• Does this pull request introduce a new feature? yes
• If yes, how is the feature documented? JavaDocs

[slfan1989]

@zhoujinsong Could you please help review this PR when available? Thank you very much!