Add dns search domains from cni response to resolv.conf

[Luap99]

This fixes slow local host name lookups.
see containers/dnsname#57

[vrothberg]

LGTM

[vrothberg]

@Luap99 do you have numbers regarding the performance improvements?

[Luap99]

@vrothberg

$ sudo bin/podman run --network cni-podman3 --name test --replace alpine time nslookup test
c0b65c64d56331e62bb0c8e86a1f53c3b6e4ce5932dfe0267e59f7f727b55cc0
Server:         10.89.2.1
Address:        10.89.2.1:53

Name:   test
Address: 10.89.2.8

real    0m 0.12s
user    0m 0.00s
sys     0m 0.00s
$ sudo bin/podman run --network cni-podman3 --dns-search dns.podman  --name test --replace alpine time nslookup test
59e759d47947eed1cf31d46f0e0295829c2632f54dcd11ece8ec03481afbe50b
Server:         10.89.2.1
Address:        10.89.2.1:53

Name:   test.dns.podman
Address: 10.89.2.9

Non-authoritative answer:
real    0m 0.00s
user    0m 0.00s
sys     0m 0.00s

You can test by adding --dns-search dns.podman. also see containers/dnsname#55

[Luap99]

@vrothberg It is not really consistent sometime it is also fast without the search domain. I also believe this is the reason why dnsname test failed in my rootless network PR and only worked after adding dns.podman

[Luap99]

It also looks like it was needed for ubuntu #9385

[rhatdan]

/approve
/lgtm

[openshift-ci-robot]

[APPROVALNOTIFIER] This PR is APPROVED

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[developedsoftware]

What version of podman was this released under?

[Luap99]

v3.1
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