Bug 1441617 - Remove duplicate require() from perf entrypoint

The filters file is already `require()`ed higher up in the file.
This avoids an eslint error once these are switched to ES6 imports.

ui/entry-perf.js

@@ -50,4 +50,3 @@ require('./js/components/perf/compare.js');
 require('./js/components/auth.js');
 require('./js/components/loading.js');
 require('./js/perfapp.js');
-require('./js/filters.js');