fix: use a single translator for middleware (#10633)

# Which Problems Are Solved

Comparing the v3 and v4 deployments we noticed an increase in memory
usage. A first analysis revealed that it might be related to the
(multiple) initialization of the `i18n.Translator`, partially related

# How the Problems Are Solved

Initialize the tranlator once (apart from the translator interceptor,
which uses context / request specific information) and pass it to all
necessary middleware.

# Additional Changes

Removed unnecessary error return parameter from the translator
initialization.

# Additional Context

- noticed internally
- backport to v4.x

internal/notification/handlers/translator.go

@@ -14,10 +14,7 @@ func (n *NotificationQueries) GetTranslatorWithOrgTexts(ctx context.Context, org
 	if err != nil {
 		return nil, err
 	}
-	translator, err := i18n.NewNotificationTranslator(n.GetDefaultLanguage(ctx), restrictions.AllowedLanguages)
-	if err != nil {
-		return nil, err
-	}
+	translator := i18n.NewNotificationTranslator(n.GetDefaultLanguage(ctx), restrictions.AllowedLanguages)
 
 	allCustomTexts, err := n.CustomTextListByTemplate(ctx, authz.GetInstance(ctx).InstanceID(), textType, false)
 	if err != nil {