Remove SimpleStore cache
Remove SimpleStore cache

SimpleStore is instantiated anew most of the times it's used, so having
a cache inside it serves no purpose. Removing it.

Reviewed-by: iustinp


yiannist/ganeti,ganeti-github-testing/ganeti-test-1,yiannist/ganeti,andir/ganeti,leshchevds/ganeti,ganeti/ganeti,apyrgio/snf-ganeti,dimara/ganeti,andir/ganeti,bitemyapp/ganeti,onponomarev/ganeti,ganeti/ganeti,grnet/snf-ganeti,apyrgio/ganeti,dimara/ganeti,andir/ganeti,apyrgio/snf-ganeti,onponomarev/ganeti,ganeti-github-testing/ganeti-test-1,bitemyapp/ganeti,yiannist/ganeti,apyrgio/ganeti,leshchevds/ganeti,mbakke/ganeti,grnet/snf-ganeti,leshchevds/ganeti,ganeti/ganeti,mbakke/ganeti,mbakke/ganeti