temporarily remove code that prevents MDM from being turned on in UI (#35292)

<!-- Add the related story/sub-task/bug number, like Resolves #123, or
remove if NA -->

# Checklist for submitter

If some of the following don't apply, delete the relevant line.

## Testing
- [x] QA'd all new/changed functionality manually

frontend/router/index.tsx

@@ -202,10 +202,6 @@ const routes = (
                   path="integrations/:section"
                   component={AdminIntegrationsPage}
                 />
-                <Route
-                  path="integrations/:section/:subsection"
-                  component={AdminIntegrationsPage}
-                />
                 <Route component={ExcludeInSandboxRoutes}>
                   <Route path="users" component={AdminUserManagementPage} />
                 </Route>