[IMPR] Use SingleSiteBot with states_redirect.py
[IMPR] Use SingleSiteBot with states_redirect.py

Bot class is noted as to be deprecated. Use SingleSitesBot instead.

- StatesRedirectBot.site is set by super class but the generator must become
  an StatesRedirectBot property
- Create the abbrev in setup method

Change-Id: Ic061ee0d8f92033c7ec1086b26f9d1dca806f2ba

wikimedia/pywikibot-core,wikimedia/pywikibot-core,PersianWikipedia/pywikibot-core