fix(expr): round to left of decimal point when 2nd arg is negative

[xiangjinwu]

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What's changed and what's your intention?

Fix #9417

Checklist

• I have written necessary rustdoc comments
• I have added necessary unit tests and integration tests
• I have added fuzzing tests or opened an issue to track them. (Optional, recommended for new SQL features Sqlsmith: Sql feature generation #7934).
• My PR contains breaking changes. (If it deprecates some features, please create a tracking issue to remove them in the future).
• All checks passed in ./risedev check (or alias, ./risedev c)
• My PR changes performance-critical code. (Please run macro/micro-benchmarks and show the results.)

• My PR contains critical fixes that are necessary to be merged into the latest release. (Please check out the details)

Documentation

• My PR contains user-facing changes.

Types of user-facing changes

• SQL commands, functions, and operators

Release note

Just like in PostgreSQL, the 2nd arg of round can now be negative, which means to round to the left of the decimal point.

[codecov]

Codecov Report

Merging #10961 (f0ce754) into main (164f069) will decrease coverage by 0.01%.
The diff coverage is 95.91%.

@@            Coverage Diff             @@
##             main   #10961      +/-   ##
==========================================
- Coverage   69.94%   69.93%   -0.01%     
==========================================
  Files        1307     1307              
  Lines      223617   223652      +35     
==========================================
+ Hits       156415   156418       +3     
- Misses      67202    67234      +32     

Flag	Coverage Δ
rust	69.93% <95.91%> (-0.01%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/connector/src/parser/avro/util.rs	50.54% <0.00%> (ø)
src/connector/src/parser/unified/avro.rs	74.27% <ø> (ø)
src/common/src/types/decimal.rs	66.77% <100.00%> (+0.33%)	⬆️
src/expr/src/vector_op/round.rs	94.00% <100.00%> (+1.50%)	⬆️

... and 2 files with indirect coverage changes

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[wangrunji0408]

LGTM!