Remove some dead file and copybara paths (#22102)

* Remove modules-main.js

* Remove history-migration from copy.bara.sky

GitOrigin-RevId: 947fb1d9655a296c228be09e7971c0060be0e5cc

services/web/modules/modules-main.js

@@ -1,3 +0,0 @@
-import importOverleafModules from '../frontend/macros/import-overleaf-module.macro'
-
-export default importOverleafModules('entryPointsMain')