fix(azure): disable use-dns for secondary nics

[aciba90]

Proposed Commit Message

fix(azure): disable use-dns for secondary nics

DNS resolution through secondary NICs is not supported on Azure. Disable
it.
    
Without this, we see seconds of delay resolving urls in cloud-init logs
from Jammy+, see SF ticket.
    
Per cjp256's comment, the first NIC under metadata.imds.network is ensured
to be the primary one. We use this to determine primary NICs instead of
relying on fragile driver and/or NIC names.
    
Fixes: SF #00380708
    
Co-authored-by: Calvin Mwadime <calvin.mwadime@canonical.com>

Additional Context

Supersedes #5180, see comments for more context.
Closes:

• https://warthogs.atlassian.net/browse/CPC-4224
• https://warthogs.atlassian.net/browse/CPC-3999
• https://bootstack.canonical.com/cases/00380708

Test Steps

make deb

export CLOUD_INIT_CLOUD_INIT_SOURCE=cloud-init_all.deb
export CLOUD_INIT_PLATFORM=azure

tox -e integration-tests -- tests/integration_tests/datasources/test_azure.py::test_azure_multi_nic_setup

Checklist

• My code follows the process laid out in the documentation
• I have updated or added any unit tests accordingly
• I have updated or added any documentation accordingly

Merge type

• Squash merge using "Proposed Commit Message"
• [] Rebase and merge unique commits. Requires commit messages per-commit each referencing the pull request number (#<PR_NUM>)

[aciba90]

@danpdraper and @cjp256, I have created this PR superseding #5180. Please review it, thanks.

[cjp256]

LGTM, thanks!! I'll be sure to verify when it lands in the daily.

[TheRealFalcon]

LGTM!

[cjp256]

Just wanted to say thanks again @aciba90! Testing looks great so far.

[aciba90]

Thank you, @cjp256, for the support and testing! Let us know if anything goes wrong.