[Mobile] Move from DATA_SPN to SPN for networkName

The old legacy pipeline would read both values from the broadcast, and
expose them in two separate places. During migration to the new
pipeline, NetworkNameModel was incorrectly using DATA_SPN rather than
SPN, which is the name that NetworkControllerImpl _mostly_ used in the
legacy code.

There is exactly one (1) place in SystemUI that had referenced the
DATA_SPN, and that was in InternetTile.java. I suspect that we either do
not need this field, or we can add it alongside of the regular
networkName field later.

For now, the fix is very simple: migrate from EXTRA_DATA_SPN to
EXTRA_SPN when extracting a network name from the
ACTION_SERVICE_PROVIDERS_UPDATED broadcast.

Test: MobileConnectionRepositoryTest
Test: manual
Bug: 350812372
Flag: com.android.systemui.FLAG_STATUS_BAR_SWITCH_TO_SPN_FROM_DATA_SPN
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:56555f63384c08d1878a43992f0606db9cbe8a58)
Merged-In: Ia2ca5790676c71c3f7575d524f7bd19db049a471
Change-Id: Ia2ca5790676c71c3f7575d524f7bd19db049a471