Fixes for run_integration_tests.sh

This script runs some useful integration tests, but is currently broken
at ToT. This CL enables us to rerun this script successfully.

Details
1. Remove the scripts related to bp2build/b/mixed_builds. These modes
   have been/are on the verge of deletion from soong
2. Remove the comparisision scripts for soong and bazel built artifcats,
   for the same reason
3. Add a TARGET_RELEASE to androidmk_test.sh
4. Add a TARGET_PRODUCT to o/s/build.ninja, since the generated .ninja files
   now have a product-specific suffix.
5. Remove a test that checks that globs are not generated in the first
   clean run. We always generate the glob file now (aosp/2893286)

Test: build/soong/tests/run_integration_tests.sh
Change-Id: I39f6706ab2a81a7b1b2e90d43195bc3e2c7a5c08