Include bazel-status of build in metrics

Currently within metrics we cannot distinguish between Bazel-involved
configurations:
  Bazel as Ninja vs Ninja as Ninja builds
  Bazel mixed builds vs non-mixed builds

Add these to the build configuration in order to distinguish between and
track them independently.

Test: go soong tests
Test: USE_BAZEL_ANALYSIS=1 m nothing and verify out/soong_metrics
Bug: 193672397
Change-Id: I94ce56c1a98a76d929598d9fe3070df16ffa1376