[release/5.0] SqlServer Migrations: Don't generate EXEC(CONCAT())

[bricelam]

Fixes #22611

Description

In 5.0 we started generating EXEC calls in idempotent migration SQL scripts to work around quirks in the SQL Server parser. Unfortunately, this code didn't integrate well with another change we made to generate CONCAT calls for string literals containing new lines. The resulting SQL--EXEC(CONCAT(...))--is invalid.

Customer Impact

This will only affect users generating idempotent migration scripts containing seed data. One customer has reported it so far.

How found

Customer reported on RC2.

Test coverage

We have tests comparing the generated SQL against a baseline. However, we don't have any tests that execute the SQL scripts due to the complexity of executing scripts containing utility statements like GO that aren't supported by SqlClient and only work in tools like SSMS, SDT, and SQLCMD. We previously failed to manually verify that the scripts executed correctly. This verification has now been done for the current baselines.

Regression?

Yes, for certain scenarios from 3.1. Although some scripts would have failed in 3.1 because of the missing EXEC calls, others would have worked that are now broken in 5.0.

cc @Pilchie

[Pilchie]

Approved (by email) for 5.0 GA.