Merge branch '3344-threadsanitizer-data-race-in-isc__nm_tcpdns_send-v9_16' into 'v9_16'

Move setting the sock->write_timeout to the async_*send [v9.16]

See merge request !6342
91 jobs for v9_16 in 291 minutes and 29 seconds (queued for 4 seconds)
Name Stage Failure
system:msvc-debug:windows:amd64 System
Built:        2021-08-22T19:47:56+0000
OS/Arch: windows/amd64
Uploading artifacts...
Runtime platform
arch=amd64 os=windows pid=296160 revision=58ba2b95 version=14.2.0
untracked: found 2140 files

Uploading artifacts as "archive" to coordinator... ok
id=2528046 responseStatus=201 Created token=McTfStCN
Cleaning up file based variables
Unsupported run stage "cleanup_file_variables"
ERROR: Job failed: exit status 1