fix(core): do not reset query_values in case of form encoding (#11654)

Author: bajajneha27

google-apis-core/lib/google/apis/core/http_command.rb

@@ -168,7 +168,6 @@ def prepare!
             @form_encoded = true
             self.body = Addressable::URI.form_encode(url.query_values(Array))
             self.header['Content-Type'] = 'application/x-www-form-urlencoded; charset=UTF-8'
-            self.url.query_values = {}
           else
             @form_encoded = false
           end

google-apis-core/spec/google/apis/core/http_command_spec.rb

@@ -444,8 +444,7 @@ class DecryptResponse
   end
 
   it 'should form encode parameters when method is POST and no body present' do
-    stub_request(:post, 'https://www.googleapis.com/zoo/animals')
-        .with(body: 'a=1&a=2&a=3&b=hello&c=&d=0')
+    stub_request(:post, 'https://www.googleapis.com/zoo/animals?a=1&a=2&a=3&b=hello&c&d=0')
         .to_return(status: [200, ''])
     command = Google::Apis::Core::HttpCommand.new(:post, 'https://www.googleapis.com/zoo/animals')
     command.query['a'] = [1,2,3]