Clear as much of cc.Module as possible after GenerateBuildActions

Reduce peak memory usage by adding a CleanupAfterBuildActions method
that is called at the end GenerateBuidlActions, nad use it to clear as
much of cc.Module as possible.

This is a temporary measure, eventually the entire module should be
released by blueprint once all interactions are performed through
providers.

Test: all soong tests pass
Change-Id: Idc3390ae4506ff2eef3231691e1de7446067961a