MSD: Collapse redundant resetLocaleData branching

Both `loadOmnibar` and the dashboard `I18nProvider` had an identical
four-line if/else that called `resetLocaleData(data)` for the success
branch and `resetLocaleData()` for the undefined branch. The two
branches are equivalent: `resetLocaleData` accepts an optional
`LocaleData` argument and passing `undefined` has the same effect as
passing nothing (both clear the data bag and reapply default-domain
metadata).

Collapse to a single `resetLocaleData( data )` call at each site.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: StevenDufresne

client/dashboard/app/i18n.tsx

@@ -135,11 +135,7 @@ export function I18nProvider( { children }: PropsWithChildren ) {
 			if ( cancelled ) {
 				return;
 			}
-			if ( data ) {
-				i18n.resetLocaleData( data );
-			} else {
-				i18n.resetLocaleData();
-			}
+			i18n.resetLocaleData( data );
 			const realLanguage = data ? language : 'en';
 			setLoadedLocale( realLanguage );
 			setLocaleInDOM( i18n, realLanguage );

client/dashboard/app/interim-omnibar/index.tsx

@@ -36,11 +36,7 @@ export default async function loadOmnibar( events: OmnibarEvents ) {
 		loadUserLocaleData( getUserLanguage( window.currentUser ?? null ) ),
 	] );
 
-	if ( localeData ) {
-		defaultI18n.resetLocaleData( localeData );
-	} else {
-		defaultI18n.resetLocaleData();
-	}
+	defaultI18n.resetLocaleData( localeData );
 
 	hydrateRoot(
 		container,