fix(mysql): cap timestamp output at microsecond precision (#9831)
* fix(mysql): cap timestamp output at microsecond precision
Truncate MySQL text timestamp results to microseconds while preserving the existing second and millisecond formatting. Keep stored nanoseconds and explicit integer/string representations unchanged.
Fixes#9828
* chore: ignore local output directory
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(cherry picked from commit 5af1e3301e)
Signed-off-by: luofucong <luofc@foxmail.com>
