fix: prevent SQL keyword parameterization in MySQL bulk_load_custom

[majiayu000]

Fixes incorrect SQL keyword parameterization in MySqlHook.bulk_load_custom() that causes MySQL drivers to quote IGNORE/REPLACE keywords as string literals, producing invalid SQL.

Problem

bulk_load_custom() passes duplicate_key_handling (e.g., IGNORE, REPLACE) and extra_options as parameterized query values via cursor.execute(sql, parameters). The MySQL driver treats parameterized values as data and quotes them as string literals, producing invalid SQL like:

LOAD DATA LOCAL INFILE '/tmp/file' 'IGNORE' INTO TABLE `my_table` 'FIELDS TERMINATED BY ...'

This was introduced in PR #33328 which changed from string concatenation to parameterization for these keywords.

Root Cause

In providers/mysql/src/airflow/providers/mysql/hooks/mysql.py, the bulk_load_custom method builds the SQL as:

sql_statement = f"LOAD DATA LOCAL INFILE %s %s INTO TABLE `{table}` %s"
parameters = (tmp_file, duplicate_key_handling, extra_options)

Both duplicate_key_handling and extra_options are SQL syntax keywords, not data values. Only tmp_file is actual data that should be parameterized.

Fix

Changed bulk_load_custom to interpolate duplicate_key_handling and extra_options directly into the SQL statement via f-string, while keeping tmp_file as the sole parameterized value:

sql_statement = f"LOAD DATA LOCAL INFILE %s {duplicate_key_handling} INTO TABLE `{table}` {extra_options}"
parameters = (tmp_file,)

Updated existing tests (test_bulk_load_custom, test_bulk_load_custom_hook_lineage) to assert the new SQL shape and parameter tuple. Added a new parametrized test test_bulk_load_custom_duplicate_key_not_parameterized that validates both IGNORE and REPLACE appear literally in the executed SQL and only tmp_file is parameterized.

closes: #62506

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Was generative AI tooling used to co-author this PR?

• Yes — Claude Opus 4.6

Generated-by: Claude Opus 4.6 following the guidelines

[boring-cyborg]

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[SameerMesiah97]

Fix CI and possibly a minor spacing issue and this should be good enough to merge.

[boring-cyborg]

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