I think what happens is that the catalog name from the connection string specified in the config file is used (since you have specified an empty string as the new catalog name in the sqlServerCatalogNameOverwrites).
And this doesn't get overwritten by the connection string specified in code.
So your options are:
1- Specify "FSV-dev" as the new catalog name in the sqlServerCatalogNameOverwrites.
OR
2- Specify "FSV-dev" in the connection string in the config file
OR
3- If you need the catalog name to be set dynamically in code, then only remove the connection string from the config file.