VCN: Remove hidden APIs for build type and vcn service string

This is a preparation CL for moving VCN to a mainline module

Bug: 288465472
Test: atest FrameworksVcnTest && atest CtsVcnTestCases
Flag: EXEMPT pure refactoring
Change-Id: Ifb834448f1aafb2aa7eacd11981473405b39eddf
2 files changed