Use our own copy of the Codecov uploader (#74460)

Due to the recent security incident, use our own copy hosted in S3
to mitigate future risk from running an arbitrary script downloaded from a
remote and untrtusted server.

.azure-pipelines/scripts/publish-codecov.sh

@@ -7,7 +7,7 @@ set -o pipefail -eu
 
 output_path="$1"
 
-curl --silent --show-error https://codecov.io/bash > codecov.sh
+curl --silent --show-error https://ansible-ci-files.s3.us-east-1.amazonaws.com/codecov/codecov.sh > codecov.sh
 
 for file in "${output_path}"/reports/coverage*.xml; do
     name="${file}"