Change storage behavior of multiproduct_kati

Instead of deleting artifacts/logs from successful build (unless -keep
is set), and keeping unsuccessful artifacts, keep all logs and remove
all artifacts (unless -keep is set, then we'll compress the artifacts).

If -dist is passed in, we'll put an archive of the logs into the
DIST_DIR. Even compressed, the rest of the artifacts are still a bit too
large to dist (~5.6GB on AOSP).

Test: build/soong/build_test.bash
Test: build/soong/build_test.bash -keep
Test: build/soong/build_test.bash -dist
Change-Id: I87f55978c18c8ff2e517b8271554ba383003742f