Remove use of httputil reverse proxy

[phillebaba]

This change removes the httputil reverse proxy in favor of a http client. This is mostly to remove complexity and add some control back to outgoing requests. We aren't in need of a lot of the proxy features anyways as the outgoing requests are known.

[codecov]

Codecov Report

Attention: Patch coverage is 76.56250% with 15 lines in your changes missing coverage. Please review.

Files with missing lines	Patch %	Lines
pkg/registry/registry.go	76.56%	11 Missing and 4 partials ⚠️

Files with missing lines	Coverage Δ
pkg/registry/registry.go	50.48% <76.56%> (+1.57%)	⬆️