Only retry test-results uploading if we don't get a 5xx error code.
Only retry test-results uploading if we don't get a 5xx error code.

BUG=537341

Review URL: https://codereview.chromium.org/1384553002

git-svn-id: 239fca9b83025a0b6f823aeeca02ba5be3d9fd76@296992 0039d316-1c4b-4281-b951-d872f2087c98

eunchong/build,eunchong/build,eunchong/build,eunchong/build