gen: Remove leading 'x' from repository name
gen: Remove leading 'x' from repository name

The leading 'x' is kind of arbitrary. Especially now that we can set
topics on the repositories, we don't need a pattern to distinguish what
is a track or not.

The repository itself has already been renamed.

See https://github.com/exercism/meta/issues/1

exercism/xgo,leenipper/xgo,exercism/xgo,robphoenix/exercism-go,leenipper/xgo,robphoenix/exercism-go