Remove frontend check for collections feature flag (#39215)

app/javascript/mastodon/utils/environment.ts

@@ -12,7 +12,7 @@ export function isProduction() {
   else return import.meta.env.PROD;
 }
 
-export type ServerFeatures = 'fasp' | 'collections';
+export type ServerFeatures = 'fasp';
 
 export function isServerFeatureEnabled(feature: ServerFeatures) {
   return initialState?.features.includes(feature) ?? false;