msp/deploy: add 'author' and 'commit_message' annotations (#63108)

Add 'author' and 'commit_message' annotations on release

## Test plan
CI

Author: jac

dev/ci/msp_deploy.sh

@@ -11,18 +11,14 @@ set -eux -o pipefail
 # CI Variables
 : "${BUILDKITE_BUILD_NUMBER:?"BUILDKITE_BUILD_NUMBER is required"}"
 : "${BUILDKITE_COMMIT:?"BUILDKITE_COMMIT is required"}"
-
-# TODO: figure out a good way to capture author details
-# can contain only lowercase letters, numeric characters, underscores, and dashes.
-# All characters must use UTF-8 encoding, and international characters are allowed.
-# Keys must start with a lowercase letter or international character
-# : ${BUILDKITE_BUILD_AUTHOR_EMAIL:?"BUILDKITE_BUILD_AUTHOR_EMAIL is required"}
+: "${BUILDKITE_BUILD_AUTHOR:?"BUILDKITE_BUILD_AUTHOR is required"}"
 
 # Computed Variables
 GCP_CLOUDRUN_SKAFFOLD_SOURCE="gs://${GCP_PROJECT}-cloudrun-skaffold/source.tar.gz"
 GCP_DELIVERY_PIPELINE="${MSP_SERVICE_ID}-${GCP_REGION}-rollout"
 SHORT_SHA="${BUILDKITE_COMMIT:0:12}"
 TAG="${SHORT_SHA}_${BUILDKITE_BUILD_NUMBER}"
+COMMIT_MESSAGE="$(git log -n 1 --pretty=format:'%s')"
 # resource ids must be lower-case letters, numbers, and hyphens,
 # with the first character a letter, the last a letter or a number,
 # and a 63 character maximum
@@ -43,4 +39,4 @@ gcloud=$2
     --source="${GCP_CLOUDRUN_SKAFFOLD_SOURCE}" \
     --labels="commit=${BUILDKITE_COMMIT}" \
     --deploy-parameters="customTarget/tag=${TAG}" \
-    --annotations="commit=${BUILDKITE_COMMIT}"
+    --annotations="commit=${BUILDKITE_COMMIT},author=${BUILDKITE_BUILD_AUTHOR},commit_message=${COMMIT_MESSAGE}"