Fix inline comments (--) on the last line of an incremental model (partition replacement)

[tnk-ysk]

resolves #896
docs dbt-labs/docs.getdbt.com/#

Problem

If an incremental model (with static partition replacement) has an inline SQL comment, this results in an invalid SQL statement.

Solution

Change so that there is a line break after the SQL.
Test has not been added as it is expected to be added by dbt-labs/dbt-core#8487

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

[tnk-ysk]

@mikealfare
Sorry to bother you again.
I fixed test case because it was invalid.
Adding comment to existing test case was sufficient.