build-perf-test-wrapper.sh: store buildstats under git-notes

In order to dramatically reduce the data footprint of the result
branches. This makes cloning/pulling result repositories a lot faster.
Buildstats can still be accessed, when needed by doing
git fetch refs/notes/buildstats/*:refs/notes/buildstats/*

[YOCTO #10582]

(From OE-Core rev: 5b52bbf09bb2fbec9d2d54f3c3c46c74a09fbfd0)

Signed-off-by: Markus Lehtonen <markus.lehtonen@linux.intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

scripts/contrib/build-perf-test-wrapper.sh

@@ -143,6 +143,8 @@ if [ -n "$results_repo" ]; then
         --git-dir "$results_repo" \
         --branch-name "{hostname}/{branch}/{machine}" \
         --tag-name "{hostname}/{branch}/{machine}/{commit_count}-g{commit}/{tag_number}" \
+        --exclude "buildstats.json" \
+        --notes "buildstats/{branch_name}" "$results_dir/buildstats.json" \
         "$results_dir"
 fi