fix: [microbatch] delete redundant using clause

[ugmuka]

resolves #1198

Problem

The microbatch feature generates a DELETE SQL statement that includes a redundant USING clause. The current SQL looks like this:

delete from <target_model_name> DBT_INTERNAL_TARGET
    using <tmp_table>
    where (
    DBT_INTERNAL_TARGET.event_date >= TIMESTAMP '2024-10-13 00:00:00+00:00'
    and DBT_INTERNAL_TARGET.event_date < TIMESTAMP '2024-10-14 00:00:00+00:00'
    
    );

This results in a Cartesian join, which is unnecessary. To resolve this issue, the USING <tmp_table> clause should be removed.

Solution

Remove the USING <tmp_table> clause from merge.sql.

Checklist

• I have read the contributing guide and understand what's expected of me
• I have run this code in development and it appears to resolve the stated issue
• This PR includes tests, or tests are not required/relevant for this PR
• This PR has no interface changes (e.g. macros, cli, logs, json artifacts, config files, adapter interface, etc) or this PR has already received feedback and approval from Product or DX

[cla-bot]

Thanks for your pull request, and welcome to our community! We require contributors to sign our Contributor License Agreement and we don't seem to have your signature on file. Check out this article for more information on why we have a CLA.

In order for us to review and merge your code, please submit the Individual Contributor License Agreement form attached above above. If you have questions about the CLA, or if you believe you've received this message in error, please reach out through a comment on this PR.

CLA has not been signed by users: @ugmuka

[ugmuka]

I have signed CLA.

[colin-rogers-dbt]

@cla-bot check

[cla-bot]

The cla-bot has been summoned, and re-checked this pull request!

[MichelleArk]

Closing in favor of an equivalent fix that went out in: https://github.com/dbt-labs/dbt-snowflake/pull/1192/files#diff-03ee8d11934e66a23fa4ab1a018378a9533816c757ed0c709fad89ada1d12d79L69