feat: Enhance user group management and transaction handling in stored procedures

- Improved user group deletion logic to accurately report success or failure.
- Updated user group renaming checks to prevent unintended inserts or updates.
- Added documentation on transaction blocking risks during full resets in stored procedures.
- Removed unnecessary login scripts from database project.

Fuchs_Database/Security/fuchs_fds.login.sql

@@ -1,6 +0,0 @@
--- Server-level login referenced by the [fuchs_fds] database user.
--- Exists only so the project model resolves (SQL71501); the real password
--- is managed on the server and never taken from this script.
-CREATE LOGIN [fuchs_fds]
-    WITH PASSWORD = N'placeholder-not-deployed';
-

Fuchs_Database/Security/fuchs_web.login.sql

@@ -1,6 +0,0 @@
--- Server-level login referenced by the [fuchs_web] database user.
--- Exists only so the project model resolves (SQL71501); the real password
--- is managed on the server and never taken from this script.
-CREATE LOGIN [fuchs_web]
-    WITH PASSWORD = N'placeholder-not-deployed';
-