refactor(api): remove newTestServerWithOptions and spoofed IP rejection test

- Simplified test server initialization by removing `newTestServerWithOptions`.
- Deleted `TestManagementLocalPasswordRejectsSpoofedForwardedFor` as spoofed IP handling is no longer applicable.
- Removed trusted proxy configuration from Gin engine setup.

internal/api/server.go

@@ -217,9 +217,6 @@ func NewServer(cfg *config.Config, authManager *auth.Manager, accessManager *sdk
 
 	// Create gin engine
 	engine := gin.New()
-	if errSetTrustedProxies := engine.SetTrustedProxies(nil); errSetTrustedProxies != nil {
-		log.Warnf("failed to disable trusted proxy headers: %v", errSetTrustedProxies)
-	}
 	if optionState.engineConfigurator != nil {
 		optionState.engineConfigurator(engine)
 	}