fix(gitlab): Handle JSONDecodeError

[MeredithAnya]

We are getting a JSONDecodeError when gitlab responds back with a 301 on refreshing identities because we attempt to get the status code from the decoded json when there isn't any. Let's just use the response code from the req so that we actually can log the refresh failures (currently we aren't logging it at all)

FIXES SENTRY-RKE

[mgaeta]

I think we should only use req.status_code when the error type is JSONDecodeError and in all other cases user e.code. We could do something like

"error_status": e.code if hasattr(e, "code") else req.status_code,

or

"error_status": getattr(e, "code", req.status_code),

or

except JSONDecodeError as e:
  code = req.status_code
  self.logger(...)
except Exception as e:  
  code = e.code
  self.logger(...)

[mgaeta]

Looks good but you should leave a comment explaining why e.code might not exist.