Moving "No unrecognized messages found in build log" out of stderr
Moving "No unrecognized messages found in build log" out of stderr

so that most users won't see it in build_error.log

Bug: 171003121
Test: rm ../../out -rf && OUT_DIR=../../out ./busytown/impl/build.sh :core:core:assemble -Pandroidx.validateNoUnrecognizedMessages >/dev/null # and see that this message doesn't appear
Change-Id: Id6f824d9180d5d111eedd538eff690afe53e8a29

AndroidX/androidx,androidx/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,androidx/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,AndroidX/androidx,AndroidX/androidx,androidx/androidx,AndroidX/androidx,AndroidX/androidx,androidx/androidx