Fix running ns tests may print error

[bpringe]

What has Changed?

• Filters test results to get only actual results. (Filters out nrepl messages saying a namespace was not found when tests were run for a non-existing namespace.)

Fixes #1516

My Calva PR Checklist

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Ping @PEZ, @bpringe

[marcomorain]

thanks for taking care of this 🙏

[bpringe]

No problem!