Fix how we evaluate whether DBS is global or not

[amaltaro]

While looking at this code:
https://github.com/dmwm/WMCore/blob/master/src/python/WMCore/WorkQueue/DataLocationMapper.py#L24

which makes a couple of calls to figure out whether our DBS instance is talking to the global DBSServer instance or not, I noticed it calls getServerInfo, which does NOT exist either in the DBSReader nor in DbsApi.

The DBSReader instance has this attribute:

>>> d.dbsURL
'https://cmsweb-testbed.cern.ch/dbs/int/global/DBSReader/'

while the DbsApi has

>>> dbs.url
'https://cmsweb-testbed.cern.ch:8443/dbs/int/global/DBSReader/'

thus it's one less http request made to the DBSServer.

[amaltaro]

@khurtado Kenyi, this one is supposed to be a simple issue. Can you please try to get it done before your day is over? I'll then add it to the next tag to be requested to Lina, tomorrow.

[amaltaro]

I have a possible fix for it in: #9311