init: Separate the required modules of core and recovery variants

So that init_second_stage (core) depends on core variant tools and rc
files, and init_second_stage.recovery depends on recovery variant tools
and recovery specific rc files.

Bug: 191369319
Test: Presubmit
Test: Check the ninja graph, init_second_stage.recovery no longer depend
  on core variation modules
Test: Check out/soong/Android-${PRODUCT}.mk
Change-Id: I03f0cf6af10617fe2e7de677e9dde1aecb2afc74