lineage: Disable IPv4 for T-Mobile (and MetroPCS) domestically

* T-Mobile's domestic network is IPv6 only, and T-Mobile
  support recommends setting IPv6 only for max compat
* T-Mobile support also recommends IPv4 only for roaming,
  however compat issues have been discovered in the past
* Switching to IPv6 only domestically fixes an issue with
  literal IPv4 addresses failing to resolve properly on ether

Change-Id: I7e394c6b7eebf9c106eaea5e000fe021adf421e6

prebuilt/common/etc/apns-conf.xml

@@ -1386,11 +1386,11 @@
   <apn carrier="WCW Internet" mcc="310" mnc="180" apn="internet.wcc.net" user="3257630000" password="mmsc" type="default,supl" authtype="0" />
   <apn carrier="WCW-MMS" mcc="310" mnc="180" apn="mms.wcc.net" proxy="209.55.70.246" port="80" mmsc="http://mms.wcc.net" mmsproxy="209.55.70.246" mmsport="80" user="13257630000" password="mmsc" type="mms" authtype="3" />
   <apn carrier="WCW-MMS only" mcc="310" mnc="180" apn="mms.wcc.net" proxy="209.55.70.244" port="80" mmsc="http://mms.wcc.net" mmsproxy="209.55.70.246" mmsport="80" user="3257630000" password="mmsc" type="default,mms" authtype="3" />
-  <apn carrier="T-Mobile US LTE" mcc="310" mnc="260" apn="fast.t-mobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" type="default,supl,mms,ia" protocol="IPV4V6" roaming_protocol="IPV4V6" mtu="1440" />
+  <apn carrier="T-Mobile US LTE" mcc="310" mnc="260" apn="fast.t-mobile.com" mmsc="http://mms.msg.eng.t-mobile.com/mms/wapenc" type="default,supl,mms,ia" protocol="IPV6" roaming_protocol="IPV4V6" mtu="1440" />
   <apn carrier="Project Fi - T" mcc="310" mnc="260" apn="h2g2" type="ia" protocol="IPV4V6" roaming_protocol="IPV4V6" mvno_match_data="31026097" mvno_type="IMSI" />
   <apn carrier="Project Fi - T" mcc="310" mnc="260" apn="h2g2" user="none" server="*" password="none" mmsc="http://mmsc1.g-mms.com/mms/wapenc" protocol="IPV6" roaming_protocol="IP" mvno_match_data="31026097" mvno_type="IMSI" />
   <apn carrier="T-Mobile IMS" mcc="310" mnc="260" apn="ims" type="ims" modem_cognitive="true" protocol="IPV6" />
-  <apn carrier="MetroPCS 260" mcc="310" mnc="260" apn="fast.metropcs.com" protocol="IPV4V6" roaming_protocol="IPV4V6" mvno_match_data="6D" mvno_type="gid" type="ia" mtu="1440" />
+  <apn carrier="MetroPCS 260" mcc="310" mnc="260" apn="fast.metropcs.com" protocol="IPV6" roaming_protocol="IPV4V6" mvno_match_data="6D" mvno_type="gid" type="ia" mtu="1440" />
   <apn carrier="MetroPCS 260" mcc="310" mnc="260" apn="fast.metropcs.com" mmsc="http://metropcs.mmsmvno.com/mms/wapenc" protocol="IPV6" roaming_protocol="IP" mvno_match_data="6D" mvno_type="gid" type="default,supl,mms,dun" mtu="1440" />
   <apn carrier="MetroPCS 260 IMS" mcc="310" mnc="260" apn="ims" type="ims" mvno_match_data="6D" mvno_type="gid" protocol="IPV6" roaming_protocol="IPV6" mtu="1440" />
   <apn carrier="Net10" mcc="310" mnc="260" apn="wap.tracfone" port="8080" mmsc="http://mms.tracfone.com" type="default,mms,supl" />