add java_import to mixed build

Bug: 220168131
Test: go test ./java -run TestImportMixedBuild
Test: USE_BAZEL_ANALYSIS=1 m CtsManagedProfileApp && verify jars are
  included from execroot/__main__ directory
Test: build/bazel/ci/mixed_droid.sh
Change-Id: I6d35a2389ea35525d532efc8474c71d2c8825646