Remove reference to GHAE as part of the GDP

Based on a customer inquiry [Zendesk ticket](https://github.zendesk.com/agent/tickets/1012217) the docs imply that GHAE is available via the GDP. This is [not the case](https://github.slack.com/archives/C01DF2B8SAW/p1612819012035400) currently and so should be removed to prevent further customer confusion. 

cc: @bdougie

content/developers/overview/github-developer-program.md

@@ -19,7 +19,7 @@ Build your own tools that seamlessly integrate with the place you push code ever
 
 ## Take on the enterprise
 
-[Obtain developer licenses](http://github.com/contact?form%5Bsubject%5D=Development+licenses) to build and test your application against {% data variables.product.prodname_ghe_server %} or {% data variables.product.prodname_ghe_managed %}.
+[Obtain developer licenses](http://github.com/contact?form%5Bsubject%5D=Development+licenses) to build and test your application against {% data variables.product.prodname_ghe_server %}.
 
 
 ## Have an integration that works with GitHub?