sp_BlitzFirst: Remove @@ROWCOUNT to prevent errors while server is starting up

[BrentOzar]

Version of the script
SELECT @Version = '8.13', @VersionDate = '20230215';

What is the current behavior?
If you run sp_BlitzFirst while SQL Server is first starting up, AND it's recovering an In-Memory OLTP database, the @@rowcount will fail.

What is the expected behavior?
Run without failing. The fix is actually easy here - I'll switch the @@rowcount to an existence check in the table we just inserted into.

Which versions of SQL Server and which OS are affected by this issue? Did this work in previous versions of our procedures?
All versions.