Test command.process is flaky

[bbannier]

We execute the zeekctl test suite as part the nightly Zeek CI. The test command.process sometimes fails, e.g., https://cirrus-ci.com/task/6024187096072192.

[ #3] command.process ... failed
  % 'bash /zeek/auxil/zeekctl/testing/.tmp/command.process/process.test' failed unexpectedly (exit code 1)
  % cat .stderr
  + touch /zeek/auxil/zeekctl/build/testing/test.30516/share/zeek/site/test123.zeek
  + touch /zeek/auxil/zeekctl/build/testing/test.30516/share/zeek/site/test456.zeek
  + touch /zeek/auxil/zeekctl/build/testing/test.30516/share/zeek/site/test789.zeek
  + zeekctl install
  + test '!' -e /zeek/auxil/zeekctl/build/testing/test.30516/spool/tmp/testing
  + zeekctl process /zeek/auxil/zeekctl/testing/Traces/dns-session.trace
  + grep -v rotate_file_by_name orig-out
  + test -d /zeek/auxil/zeekctl/build/testing/test.30516/spool/tmp/testing
  + zeekctl process /zeek/auxil/zeekctl/testing/Traces/dns-session.trace -p test
  + grep '^-p test ' /zeek/auxil/zeekctl/build/testing/test.30516/spool/tmp/testing/.cmdline
  + zeekctl process /zeek/auxil/zeekctl/testing/Traces/dns-session.trace -- test123.zeek test456.zeek
  + grep 'test123.zeek test456.zeek$' /zeek/auxil/zeekctl/build/testing/test.30516/spool/tmp/testing/.cmdline
  + zeekctl process /zeek/auxil/zeekctl/testing/Traces/dns-session.trace -p opt2 -- test789.zeek
  + cleanup
  + set +x