Revert "Expose IPsec tunnel APIs from @SystemApi to public APIs"

This reverts commit c92a798ee83e779bd31e16554d02163b1228ae40.

Reason for revert: not necessary, since VCN already has access to system APIs

Bug: 174606949
Test: revert with no conflicts
Change-Id: Ife2d0fc08c540265d52cdf930d0b6df005990ac8
3 files changed