add graceful shutdown
as suggested by @eric in mesa#11720 (comment 2530475), it would be great if ci could signal deqp-runner to write out results for the current jobs and then exit without starting more jobs
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as suggested by @eric in mesa#11720 (comment 2530475), it would be great if ci could signal deqp-runner to write out results for the current jobs and then exit without starting more jobs