chore: revert "fix: preserve root-cause errors in KMSMasterKey exception chaining" - #810

Node.js 20 is deprecated. The following actions target Node.js 20 but are being forced to run on Node.js 24: aws-actions/configure-aws-credentials@v2. For more information see: https://github.blog/changelog/2025-09-19-deprecation-of-node-20-on-github-actions-runners/