Unbreak tethering for no offload supported devices

Catch NoSuchElementException to unbreak no offload devices.

To consistent with fetching offload config service, retry fetcheing
offload control service.
b/152430668#comment4 assert that the fetch will be retried only
if the service is installed on the device.

Bug: 155026033
Test: run TetheringCoverageTests in virtual devices(do not support
offload)

Change-Id: Ie0a32a9062c722327a27c6de13e3bb8d9588bebb