Simplify the logic in the documentation.

Author: rafaelfranca

guides/source/testing.md

@@ -891,10 +891,12 @@ you have to add remote `url`  and set `browser` as remote through `options`.
 require "test_helper"
 
 class ApplicationSystemTestCase < ActionDispatch::SystemTestCase
-  options = {
-    browser: ENV["SELENIUM_REMOTE_URL"].blank? ? :chrome : :remote,
-    url: ENV["SELENIUM_REMOTE_URL"].blank? ? nil : ENV["SELENIUM_REMOTE_URL"]
-  }
+  url = ENV.fetch("SELENIUM_REMOTE_URL", nil)
+  options = if url
+    { browser: :remote, url }
+  else
+    { browser: :chrome }
+  end
   driven_by :selenium, using: :headless_chrome, options: options
 end
 ```