Allow emergency data on bootstrap SIM

For emergency network request, always fetch the non-bootstrap
emergency APN from the APN database. Also exclude emergency data
usage from the total data usage calculation.

Bug: 319319590
Test: atest FrameworksTelephonyTests
Test: Manual test at b/332619961 & b/319319590#comment73
Test: Basic test @ b/332640742#comment1

Merged-In: I178f92708f9579144f0c7c756874c8f7e41c1365
Change-Id: I178f92708f9579144f0c7c756874c8f7e41c1365