gnu: Remove redundant wrapping from packages using ruby-build-system.

Now that the build system does wrapping automatically, it can be removed from
the packages that do it manually.

* gnu/packages/databases.scm (es-dump-restore)[arguments]: Remove #:phases.
* gnu/packages/ruby.scm (ruby-redcloth)[arguments]: Remove #:phases.
  (ruby-httpclient)[arguments]: Remove 'wrap-bin-httpclient from the modified
  phases.