[libc++][ci] Add arch and os tags to the macOS CI builders

NOKEYCHECK=True
GitOrigin-RevId: 87bfc49db5d441c6e917daeb695e105cc1982ed2
diff --git a/utils/ci/macos-ci-setup b/utils/ci/macos-ci-setup
index f9bf488..0ccf401 100755
--- a/utils/ci/macos-ci-setup
+++ b/utils/ci/macos-ci-setup
@@ -18,9 +18,10 @@
 CFG_DIR="$(brew --prefix)/etc/buildkite-agent"
 
 version="$(sw_vers -productVersion | sed -E 's/([0-9]+).([0-9]+).[0-9]+/\1.\2/')"
+arch="$(uname -m)"
 
 # Setup the tags of the agent
-echo "tags=\"queue=libcxx-builders-macos,queue=libcxx-builders-macos${version}\"" >> "${CFG_DIR}/buildkite-agent.cfg"
+echo "tags=\"queue=libcxx-builders,arch=${arch},os=macos${version}\"" >> "${CFG_DIR}/buildkite-agent.cfg"
 
 # Setup the BuildKite Agent token
 sed -i '' "s/xxx/${BUILDKITE_AGENT_TOKEN}/g" "${CFG_DIR}/buildkite-agent.cfg"