They cause flakies when different tests start them in parallel, and also
make the specs more complicated.

They read like this:

```
/home/runner/work/rubygems/rubygems/bundler/tmp/gems/base/ruby/3.4.0/gems/cgi-0.5.0.beta2/lib/cgi/util.rb:13: warning: method redefined; discarding old rfc1123_date
/opt/hostedtoolcache/Ruby/3.4.3/x64/lib/ruby/3.4.0/cgi/util.rb:225: warning: previous definition of rfc1123_date was here
/home/runner/work/rubygems/rubygems/bundler/tmp/gems/base/ruby/3.4.0/gems/cgi-0.5.0.beta2/lib/cgi/util.rb:34: warning: method redefined; discarding old pretty
/opt/hostedtoolcache/Ruby/3.4.3/x64/lib/ruby/3.4.0/cgi/util.rb:246: warning: previous definition of pretty was here
/home/runner/work/rubygems/rubygems/bundler/tmp/gems/base/ruby/3.4.0/gems/cgi-0.5.0.beta2/lib/cgi/escape.rb:16: warning: method redefined; discarding old escape
/home/runner/work/rubygems/rubygems/bundler/tmp/gems/base/ruby/3.4.0/gems/cgi-0.5.0.beta2/lib/cgi/escape.rb:29: warning: method redefined; discarding old unescape
/home/runner/work/rubygems/rubygems/bundler/tmp/gems/base/ruby/3.4.0/gems/cgi-0.5.0.beta2/lib/cgi/util.rb:13: warning: method redefined; discarding old rfc1123_date
/opt/hostedtoolcache/Ruby/3.4.3/x64/lib/ruby/3.4.0/cgi/util.rb:225: warning: previous definition of rfc1123_date was here
/home/runner/work/rubygems/rubygems/bundler/tmp/gems/base/ruby/3.4.0/gems/cgi-0.5.0.beta2/lib/cgi/util.rb:34: warning: method redefined; discarding old pretty
/opt/hostedtoolcache/Ruby/3.4.3/x64/lib/ruby/3.4.0/cgi/util.rb:246: warning: previous definition of pretty was here
/home/runner/work/rubygems/rubygems/bundler/tmp/gems/base/ruby/3.4.0/gems/cgi-0.5.0.beta2/lib/cgi/escape.rb:16: warning: method redefined; discarding old escape
/home/runner/work/rubygems/rubygems/bundler/tmp/gems/base/ruby/3.4.0/gems/cgi-0.5.0.beta2/lib/cgi/escape.rb:29: warning: method redefined; discarding old unescape
```

The problem is that `rspec` loads `erb` for its configuration, which
loads `cgi/util` from system gems.

Then our tests change the `$LOAD_PATH` to make test gems installed in
tmp visible to `require`, and then they all require `cgi` as a
transitive dependency of `rack-test`, this time from `tmp` gems. This
causes system and test specific copies to be mixed together and these
warnings to be printed, but we have also observed failures in some tests
with errors like

> class variable @@accept_charset of CGI::Util is overtaken by CGI::Escape

This changes should also fix those failures.

The fix is to require all of `rack-test` (including `cgi`) before we
have changed the `$LOAD_PATH`. Because the `$LOAD_PATH` is unchanged,
RubyGems respects the version of `cgi` activated by RSpec, avoiding the
double loads.

https://github.com/rubygems/rubygems/commit/34e75465c6

Generally are "realworld" specs are the ones using VCR cassettes of real
requests. These files don't use that, so I moved them to a different
place.