[Fix](Variant) create table should not automatically add variant to key

[eldenmoon]

#36609

[eldenmoon]

run buildall

[doris-robot]

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Please clearly describe your PR:

1. What problem was fixed (it's best to include specific error reporting information). How it was fixed.
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4. Which code was refactored and why was this part of the code refactored?
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[doris-robot]

TeamCity be ut coverage result:
Function Coverage: 36.73% (9608/26156)
Line Coverage: 28.15% (79073/280937)
Region Coverage: 26.83% (40644/151487)
Branch Coverage: 23.64% (20677/87450)
Coverage Report: http://coverage.selectdb-in.cc/coverage/484a9aaab692000d4bc51b57737b651a1f5b028e_484a9aaab692000d4bc51b57737b651a1f5b028e/report/index.html