Random GitHub Actions failures on Cache/Upload

### Is there an existing issue for this?

- [x] I have searched the existing issues

### Task description

We have been getting random failures in the GitHub Actions run lately, without much details to go on. Example: https://github.com/apache/lucenenet/actions/runs/25332841634/job/74270560566?pr=1275

This appears to fail twice, first in the Cache NuGet Packages step (even though that appears to succeed in the logs):

Then in the Upload Build Artifacts step:

(Also that file count seems a bit too high for one test run...)

Re-running the failed job generally succeeds, so this is more of an annoyance than anything else.

Also, it should be noted, that this has been occurring during two pretty rough weeks for GitHub, with lots of outages. So it might be related to that.

Start with the linked GitHub Actions run and inspect the Cache NuGet Packages and Upload Build Artifacts steps, including their logs and rerun behavior. Compare the failures with the workflow configuration and recent GitHub outage context; the issue is done when the cause is identified and a documented or validated mitigation is available.

Written by the indexing model from the issue text.