prebuilt: apns-conf-cdma.xml: Fix Sprint APNs and clean up APNs for test SIM cards

- Add back and fix Sprint APN for 1x/HRPD. Corrects MMS settings and gives a
suitable APN for DcTracker to use for HRPD/EvDo.
- Remove All test SIM APNs. Since no one is running around with a test SIM and
its useless to have a bunch of APNs sharing the same MCC MNC pair.

Change-Id: I1ccbed9b3cdd456e97d205d70bf283785122de8c