Build/Test Tools: Remove code no longer used.

This removes some configuration settings and the `copyDirectory()` function.

These files are copied by `grunt copy` as of [61873].

Props peterwilsoncc.
See #64393.

git-svn-id: https://develop.svn.wordpress.org/trunk@62071 602fd350-edb4-49c9-b593-d223f7449a82