Remove attempt to nicen UploadIO in logs

In #741 I tried to do something too clever by replacing instances of
`Faraday::UploadIO` found in parameters with a human-readable string to
improve `STRIPE_LOG` logging output.

I thought I'd tested it at the time, but apparently not (or not well
enough), and this change caused the regression detailed in #742.

My findings about how Faraday encodes multipart were apparently wrong
and it does use these parameters, so here we remove the step where we
try to nicen them for logging. The logs look a little worse, but it's
not that big of a deal.

I've tested this patch against the API and confirmed that it addresses
the problem.

Fixes #742.

lib/stripe/stripe_client.rb

@@ -219,34 +219,14 @@ def initialize
       # will throw away the result of this encoder and build its body.
       def encode(hash)
         @cache.fetch(hash) do |k|
-          @cache[k] = Util.encode_parameters(replace_faraday_io(hash))
+          @cache[k] = Util.encode_parameters(hash)
         end
       end
 
       # We should never need to do this so it's not implemented.
       def decode(_str)
         raise NotImplementedError, "#{self.class.name} does not implement #decode"
       end
-
-      # Replaces instances of `Faraday::UploadIO` with a simple string
-      # representation so that they'll log a little better. Faraday won't use
-      # these parameters, so it's okay that we did this.
-      #
-      # Unfortunately the string representation still doesn't look very nice
-      # because we still URL-encode special symbols in the final value. It's
-      # possible we could stop doing this and just leave it to Faraday to do
-      # the right thing.
-      private def replace_faraday_io(value)
-        if value.is_a?(Array)
-          value.each_with_index { |v, i| value[i] = replace_faraday_io(v) }
-        elsif value.is_a?(Hash)
-          value.each { |k, v| value[k] = replace_faraday_io(v) }
-        elsif value.is_a?(Faraday::UploadIO)
-          "FILE:#{value.original_filename}"
-        else
-          value
-        end
-      end
     end
 
     def api_url(url = "", api_base = nil)

test/stripe/stripe_client_test.rb

@@ -794,16 +794,6 @@ class StripeClientTest < Test::Unit::TestCase
         assert(!trace_payload["last_request_metrics"]["request_duration_ms"].nil?)
       end
     end
-
-    context "FaradayStripeEncoder" do
-      should "replace Faraday::UploadIO instances in parameters" do
-        encoder = StripeClient::FaradayStripeEncoder.new
-        encoded = encoder.encode(foo: [
-          { file: Faraday::UploadIO.new(::File.new(__FILE__), nil) },
-        ])
-        assert_equal "foo[0][file]=FILE%3Astripe_client_test.rb", encoded
-      end
-    end
   end
 
   class SystemProfilerTest < Test::Unit::TestCase