[10996] - use 'ip' structured data to safely retrieve default route interface

[mosys0815]

Using ip route structured data allows to query safely the default route interface, no matter the output of the standard 'ip route' output.

[boring-cyborg]

Congratulations on your first Pull Request and welcome to the Apache CloudStack community! If you have any issues or are unsure about any anything please check our Contribution Guide (https://github.com/apache/cloudstack/blob/main/CONTRIBUTING.md)
Here are some useful points:

• In case of a new feature add useful documentation (raise doc PR at https://github.com/apache/cloudstack-documentation)
• Be patient and persistent. It might take some time to get a review or get the final approval from the committers.
• Pay attention to the quality of your code, ensure tests are passing and your PR doesn't have conflicts.
• Please follow ASF Code of Conduct for all communication including (but not limited to) comments on Pull Requests, Issues, Mailing list and Slack.
• Be sure to read the CloudStack Coding Conventions.
  Apache CloudStack is a community-driven project and together we are making it better 🚀.
  In case of doubts contact the developers at:
  Mailing List: [email protected] (https://cloudstack.apache.org/mailing-lists.html)
  Slack: https://apachecloudstack.slack.com/

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 17.54%. Comparing base (4d46bec) to head (6b9c422).
⚠️ Report is 331 commits behind head on main.

Additional details and impacted files

@@             Coverage Diff              @@
##               main   #11800      +/-   ##
============================================
+ Coverage     16.57%   17.54%   +0.96%     
- Complexity    13987    15467    +1480     
============================================
  Files          5746     5897     +151     
  Lines        510860   527397   +16537     
  Branches      62140    64407    +2267     
============================================
+ Hits          84696    92516    +7820     
- Misses       416690   424486    +7796     
- Partials       9474    10395     +921     

Flag	Coverage Δ
uitests	3.60% <ø> (-0.31%)	⬇️
unittests	18.60% <100.00%> (+1.12%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[weizhouapache]

it worked on ubuntu 24

# /bin/ip -j a | /bin/jq -r '.[] | .addr_info | map(select(.local == "'`/bin/ip -j r s default | /bin/jq -r '.[0] | .prefsrc'`'")) | .[].label'
eth0

however, on RHEL and variants, the path of ip is not /bin/ip

# which ip
/usr/sbin/ip

[mosys0815]

well, until now plain ip is used, i could replace is with just ip, or the script can get the path beforehand, what would you prefer?

[mosys0815]

I changed the script to use short-paths for ipand jq, as like as it was before