[client] Remove duplicated file

It causes installation failure.

  /usr/bin/install: will not overwrite just-created `/usr/local/libexec/hatohol/client/static/js/hatohol_user_roles_editor.js' with `static/js/hatohol_user_roles_editor.js'
  make[3]: *** [install-nobase_dist_hatohol_clientDATA] Error 1