Refresh signal strength in CBRS case.

When there's an active CBRS subscription and it's in Service, we
allow a max rate of 10 seconds of refresh signal strength if there
are external signal strength queries.

Bug: 141371697
Test: manual

Change-Id: Ie6881b1fe9d33c1496e7b13d298a5296abafc54a
Merged-In: Ie6881b1fe9d33c1496e7b13d298a5296abafc54a