Log codebuild webhook trigger

[0618]

Modified from #13735

There are several ways to trigger e2e tests:

1. manually trigger it in a PR
2. e2e test branch
3. dev branch after a PR is merged

In order to know the status of the repo, we need to be notified timely when e2e test fails after a merge. So, we need to have a way to differentiate 3) from 1) and 2).

This PR is to add echos to log some infomation so that we'll be able to know in the builds log:

1. how the build is triggered
2. if the build was success

We the 2 info above, Cloudwatch is able to filter the datapoints and create a new metric so that we can set alarm from the metric.

Description of changes

log CODEBUILD_WEBHOOK_TRIGGER if a batch fails

Issue #, if available

Description of how you validated changes

Checklist

• PR description included
• yarn test passes
• Tests are changed or added
• Relevant documentation is changed or added (and PR referenced)
• New AWS SDK calls or CloudFormation actions have been added to relevant test and service IAM policies
• Pull request labels are added

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.