Remove dead code.

Nx repo metadata api was originally using
Restlet Client as transport, but it was
reworked to use Hc4Provider since introduction
of it. This code is not used since then,
and the restlet deps are unneeded also.
These classes got duplicated by collapse

Or were duplicated before collapse? Anyway,
removed the dupes.
Not exactly a dead code but...

This IT was testing Jetty from test harness for
it's proxy servlet authentication.

Nothing to do with Nexus.

Original commit introducing it:
https://github.com/sonatype/nexus/commit/a2d34298f09b16d58a1c4cf68278ea0010839f3e
Merge pull request #14 from sonatype/remove-dead-code

Remove dead code