[PLUGIN-1957] Autodetect PK Chunking for incremental loads

[harishhk107]

PLUGIN-1957 Autodetect PK Chunking for incremental loads

What

Adds a record count check before enabling PK chunking in SalesforceBatchSource.getSplits().
If the record count is below AUTO_PK_CHUNK_THRESHOLD (1,000,000), PK chunking is skipped
even if enabled in config, to avoid unnecessary overhead on small datasets. Just for DTS

Why

PK chunking is designed for very large datasets. Enabling it on small datasets causes empty
chunk overhead and increased pipeline execution time without any benefit. This change ensures
chunking is only applied when it is operationally justified by the actual record count.

Changes

SalesforceBatchSource.java —> fixed getSplits() to call shouldAutoDetectPKChunk() only when
config.getEnablePKChunk() && pkChunkCountCheck is true, added pkChunkCountCheck parameter
SalesforceSplitUtil.java —> added shouldAutoDetectPKChunk() which runs a COUNT() query
to check record count against the threshold before enabling chunking
SalesforceSourceConstants.java — added AUTO_PK_CHUNK_THRESHOLD = 1_000_000

Manual Testing

Verified pipeline runs correctly with enablePKChunk=true and small dataset → chunking skipped
Verified pipeline runs correctly with enablePKChunk=true and large dataset → chunking applied
Verified pipeline runs correctly with enablePKChunk=false → chunking skipped, no count query

For 1M records

Before ~5m 48s
After ~6m 22s

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