Add runtime test logs to HELIX_WORKITEM_UPLOAD_ROOT

[fanyang-mono]

This PR add two things:

1. Add xunit diagnostic message for long running tests over 2mins
2. Add runtime test logs to HELIX_WORKITEM_UPLOAD_ROOT, when running on CI, for better debugging test failures on CI.

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Issue Details

---

This PR add two things:

1. Add xunit diagnostic message for long running tests over 2mins
2. Add runtime test logs to HELIX_WORKITEM_UPLOAD_ROOT, when running on CI, for better debugging test failures on CI.

Author:	fanyang-mono
Assignees:	-
Labels:	area-Infrastructure-coreclr
Milestone:	-

[premun]

Cool, I can see the XHarness logs in the Helix job results now!