Add retry logic to update_package_provides.py for broken Fedora update mirrors

[mbacchi]

In the Linux build process we experience frequent errors when running the update_package_provides.py script during the build. This is because many Fedora mirrors have out of date repomd.xml files that are older than the other repository metadata files(i.e. primary.xml.gz).

19:53:24 + python update_package_provides.py
...
19:54:40   File "/usr/lib/python2.7/urllib2.py", line 531, in http_error_default
19:54:40     raise HTTPError(req.get_full_url(), code, msg, hdrs, fp)
19:54:40 urllib2.HTTPError: HTTP Error 404: Not Found
19:54:42 Build step 'Execute shell' marked build as failure
19:54:42 Finished: FAILURE

Originally I was going to whitelist the repos that were up to date(brave/brave-core#252) but I closed that in favor of adding retry logic to the script at @bridiver's recommendation.