Change default IP protocol preference from AUTO to IPV4

By default, PREFERRED_IKE_PROTOCOL_IPV4_UDP is used for safety.
This is because some carriers' networks do not support IPv6 very
well, and using IPv4 can help to prevent problems.

Carrierconfig customization on the device should override the
value if V6 are known to work well.

Bug: 269714970
Test: atest FrameworksNetTests
(cherry picked from https://android-review.googlesource.com/q/commit:4a3406799000e8f81b4b54cd8ba43bd8f8bd029b)
Merged-In: Ia0a6bd11d25fd67edb0a301e81626ec4f174155a
Change-Id: Ia0a6bd11d25fd67edb0a301e81626ec4f174155a