Fix solve the issue in SQL where the < operator is mistakenly recogni…

[shallowShark123]

…zed as <@ when used jointly with user-defined variables.
In SQL, <@ is a special binary operator. However, in MySQL parsing, if a space is added between < and @, MySQL will report a parsing error when executing. This means that '<@' does not need to be identified separately in MySQL as LT_MONKEYS_AT type.
In addition, when the < operator is mixed with user-defined variables, the token type identified by the current lexical parsing is incorrect.
For example:
select * from aaa where id > @sid
The correct identification method is that @sid is a user-defined variable, and the id field is compared with the variable using the binary operator >.
Current identification method:

@ is identified as the binary operator Array_ContainedBy, which is incorrect.

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[CLAassistant]

Thank you for your submission! We really appreciate it. Like many open source projects, we ask that you sign our Contributor License Agreement before we can accept your contribution.

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[mengnankkkk]

可补充更多边界场景，如带空格、注释、复杂表达式等，提升健壮性。
建议补充负面测试，如非法 SQL、混合操作符等。