Changed SnowflakeDialect flag div_is_floor_div to False

[sfc-gh-jmartinezramirez]

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1. What GitHub issue is this PR addressing? Make sure that there is an accompanying issue to your PR.

   Fixes SNOW-1812881: Division broken #543

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   • I am adding a new automated test(s) to verify correctness of my new code
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3. Please describe how your code solves the related issue.

   The default behavior of the flag div_is_floor_div was changed to False. This ensures that Python and Snowflake operators match the right division.

[jochenott]

Looks good. You might want to enable these sqlalchemy-provided tests again, which I believe should pass now:
https://github.com/snowflakedb/snowflake-sqlalchemy/blob/main/tests/sqlalchemy_test_suite/test_suite_20.py#L84-L99

[jochenott]

This is not how it works.

This flag is a signal from the dialect towards sqlalchemy that describes the behavior of this sql implementation (Snowflake). So if select 4/5 returns 0, div_is_floordiv must be set to True. If it returns 0.8, this flag must be set to False.

So the previous value of div_is_floordiv = True for snowflake was just a bug, which should be fixed. Just as for other bugs, there is no need to make this configurable.

[sfc-gh-jmartinezramirez]

Hi @jochenott

We agree that the correct value for the flag div_is_floordiv in Snowflake should be False. However, current users expect the / and // operators to work as true divisions, although / should behave as a true division and // as a floor division. That's why the behavioral change will be introduced as a flag, which will be removed in a future major release.

Thank you for pointing out this code issue and your contribution!!!