ganeti.http: Remove _HttpClientError
ganeti.http: Remove _HttpClientError

This is a leftover from old code.

Reviewed-by: iustinp


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