Make sure _url options accept only valid URL

... using the common validation template from oslo.config .

Note that this changes the format of prometheus_service_url option, but
this option has had no effect so far so the change may not affect users
really.

Change-Id: Idb73531dd50ce5dd29436831f6d1fbf34d54353b
Signed-off-by: Takashi Kajinami <kajinamit@oss.nttdata.com>
1 file changed