CP bugfixes from ag/13300921 to QPR3

DcTracker:
rename mRoamingUnmetered -> mNrNsaRoamingUnmetered
fix roaming logic in reevaluateUnmeteredConnections

DcTrackerTest:
reset SubscriptionPlans after tests are run

Test: atest DcTrackerTest
Bug: 178830950
Change-Id: I670751e985efb7873298ca542c7eab36a418275c
Merged-In: I8148850ea80d5a05c9e9b4b7de3c2b2b87131c14