Merge branch '3344-threadsanitizer-data-race-in-isc__nm_tcpdns_send-v9_18' into 'v9_18'

Move setting the sock->write_timeout to the async_*send [v9.18]

See merge request !6341
79 jobs for v9_18 in 42 minutes and 7 seconds (queued for 3 seconds)
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system:gcc:stretch:amd64 System
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untracked: found 1432 files

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Cleaning up project directory and file based variables
ERROR: Job failed: exit code 1