clean up and fix for dotnet-8

[TingDaoK]

Issue #, if available:

https://learn.microsoft.com/en-us/dotnet/core/compatibility/sdk/8.0/dotnet-pack-config
Starting for .NET SDK 8.0, the default configuration for dotnet build is Debug, while default configuration for dotnet pack is Release :)

Description of changes:

• set configuration for build and release explicitly, for test, using Debug
• Checked the release pipeline, we already set the configuration explicitly to Release, so that it will not affect our pipeline
• Removed the unused codebuild scripts as we moved away from codebuild CI.

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