main.addon.MonacoEditor: remove editor/editor.main.nls.js

[tobiu]

i upgraded to v0.51.0, and was missing that the setup changed.

the breaking change was not mentioned inside the release notes:
https://github.com/microsoft/monaco-editor/releases/tag/v0.51.0

i found it here:
microsoft/monaco-editor@e52ff42

[tobiu]

tried it out with removing the file, and it is causing serious damage:

i will switch back to the previous version and create a bug ticket for microsoft.