Update secrets handling

[AyodeAwe]

• Fixes the secret vulnerability mentioned by AJ here
• Upgrades the Node version from 18 to 22
• Upgrades probot version
• Converts the build system to use esbuild, reducing build size and time, and so we don't have to upload node_modules to Lambda (which has an upload size limit for deployed code)
  • build size goes from ~48MB for each function to ~3MB

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Note to Reviewers:

• I have tested by deploying the latest commit of this PR during off-hours from my local machine. This is still the currently active ops-bot deployment.
• This was potentially the only real way to test it seeing the major change in this PR is interacting with AWS Secrets Manager during start up to fetch needed secrets. Testing by deploying to AWS would ensure that we confirm that the lambda function could retreive these secrets.
• Forward merger test PR: https://github.com/rapidsai/literate-octo-potato/pull/888

Current lambda deployment screenshot (merging this PR should produce the same state in AWS shown below):