Allow ES to be published without support for IE11

[oliverfoster]

Subject of the enhancement

IE11 support is dropped by Microsoft for its core products https://techcommunity.microsoft.com/t5/microsoft-365-blog/microsoft-365-apps-say-farewell-to-internet-explorer-11-and/ba-p/1591666
IE11 will be eol after June 2022 https://docs.microsoft.com/en-us/lifecycle/faq/internet-explorer-microsoft-edge

Publishing Adapt in ES5 causes debugging issues with asynchronous call stacks as a polyfill is required to maintain compatibility, removing IE11 support will ease debugging issues.

The effect of removing ie11 support drops the adapt.min.js file size from 701KB to 500KB on grunt dev and from 507KB to 382KB on grunt build.