Revert "MM-49603 : Remove fetching of deleted channels on page load (#22981)"

This reverts commit 1bbfdefad7.

e2e-tests/playwright/support/server/default_config.ts

@@ -665,6 +665,7 @@ const defaultServerConfig: AdminConfig = {
         BoardsFeatureFlags: '',
         BoardsDataRetention: false,
         NormalizeLdapDNs: false,
+        UseCaseOnboarding: true,
         GraphQL: false,
         InsightsEnabled: true,
         CommandPalette: false,