fix: avoid duplicating trailing semicolons in executemany

[BlocksecPHD]

Fixes #2853

Pre-review checklist

• I am adding a new automated test(s) to verify correctness of my new code
• I am adding new logging messages
• I am adding a new telemetry message
• I am modifying authorization mechanisms
• I am adding new credentials
• I am modifying OCSP code
• I am adding a new dependency

Summary

This fixes the executemany(..., num_statements=...) semicolon handling in both sync and async cursors.

The current code uses re.search(";/s*$", command), which never matches trailing whitespace after a semicolon because /s is treated literally instead of as \\s. As a result, commands that already end with ; can still receive an extra ; during multi-statement concatenation.

This change replaces that check with not command.endswith(";"). executemany already normalizes the command with command.strip(" \\t\\n\\r") before this branch, so endswith(";") correctly handles the intended trailing-whitespace cases without regex.

Tests

• python3 -m pytest test/unit/test_cursor.py test/unit/aio/test_cursor_async_unit.py -k trailing_semicolon -q

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