[SandeepDave2]

Fix:
The single-connection loader previously yielded after 10,000 rows, even mid-rowset, causing unprocessed rows to be skipped.

Move the yield check after the complete fetched rowset and use >= ROWS_PER_BREAK. Cooperative yielding is preserved, the multithreaded worker/queue path is unchanged.

Addresses VTA-118774 and VTA-118542.

Verification:
Manually tested in fenced mode on Vertica 26.4.0 with PostgreSQL 15:

• Exact 10K reproduction: rowset=9999 now loads all 19,998 rows instead of 10,000, with no missing or duplicate IDs.
• 100,000-row loads pass with rowsets 100, 110, 123 and 9999.
• Single-connection fallback and four-thread range loading pass.
• Mixed-type direct COPY and external-table/CTAS values match the control.
• Empty results, cancellation rollback and same-session recovery pass.

[mkottakota1]

Discussed with Sandeep and changes are looking good