Skip running tests if only samples or markdown files have changed

[ramya-rao-a]

We logged Azure/azure-sdk-tools#1667 to allow skipping of running build or tests in PRs when the only changes are in the markdown files. This issue is an extension of that but in the context of file changes under the samples folder.

For example, see #18463 where all we did was update samples. While building the source code and running the samples related scripts are useful, running the actual tests is not

[kurtzeborn]

This should be done in all of our language repos, not jus the JS repo.

The reason we haven't supported this is because DevOps doesn't really support it. @benbp has suggested that adding a feature to support this in the test matrix generation scripts might be a possible way to tackle this.

Related question is whether GitHub actions supports this (something we'll be investigating more over the next 6 months).

[kurtzeborn]

Looking at the issue you linked to Azure/azure-sdk-tools#1667, that one is already tracking solving this generally. I'm going to go ahead and close this one since we don't want to implement a JS only solution for this. We want to do this with all of the language repos.