Remove Ikev2VpnProfileShim

Remove Ikev2VpnProfileShim and Ikev2VpnProfileBuilderShim.

The shims were only used in tests, and did not provide fallback behavior
before T, so they are not useful to keep now that all downstream
branches can build against T APIs.

Bug: 232251248
Test: atest Ikev2VpnTest
Change-Id: I3b13996c2b9560509db7a282bbf8f5adceb1c80b
(cherry picked from commit 961ac2d7993e8e21b96028e1dd6ec57559b19cac)
Merged-In: I3b13996c2b9560509db7a282bbf8f5adceb1c80b
12 files changed