Remove the temporary hack for webkit-perf.appspot.com and cleanup the code
https://bugs.webkit.org/show_bug.cgi?id=112494

Reviewed by Dirk Pranke.

Removed the code to override webkit-perf.appspot.com by perf.webkit.org.
Also merged two pairs of methods to cleanup the code.

* Scripts/webkitpy/performance_tests/perftestsrunner.py:
(PerfTestsRunner.run): Merged _upload_and_show_results.
(PerfTestsRunner._generate_results): Merged _generate_output_files.


git-svn-id: http://svn.webkit.org/repository/webkit/trunk@146150 268f45cc-cd09-0410-ab3c-d52691b4dbfc