Tweak timings in serve-stale system test

Give a little bit more time if we wait on a time out from the
authoritative (aka resolver failure), and give up after one try
(because the second attempt will likely result in a different EDE).

(cherry picked from commit f764cee1)
68 jobs for !6350 with 3341-servestale-extendederrors-test-failure-v9_18 in 33 minutes and 48 seconds (queued for 8 seconds)
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Name Stage Failure
failed
system:gcc:asan System There has been a missing dependency failure
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