Update log directory

[JunTaoLuo]

Addresses #7316.

The issue is that the log directory for functional test logs is by default $(RepoRoot)artifacts\log\ but our ci configuration publishes artifacts\logs\ instead.

There's a bunch of different ways to fix this:

1. Change the directory in ci.yml
2. Change the default functional test log from artifacts\log to artifacts\logs
3. Set an environment variable to override the default log output dir.

I opted for 1. but can easily go with another approach, especially if artifacts/logs/ is a better conventionl.

[natemcmaster]

+1, this contributes to #7280 (convert to arcade) as artifacts/log/ is the Arcade convention.

Can we take this a step further and update everything to use this folder? Add this to build/repo.props to override the KoreBuild default:

<LogOutputDir>$(ArtifactsDir)log\</LogOutputDir>