[CHAOSPLT-1360] Add DNS resolv.conf path customization for network disruptions

[aymericDD]

What does this PR do?

• Adds new functionality
• Alters existing functionality
• Fixes a bug
• Improves documentation or testing

Please briefly describe your changes as well as the motivation behind them:

Adds configuration options to specify custom resolv.conf file paths for DNS resolution in network disruptions.

• Adds injector.networkDisruption.dnsPodResolvConf config field (default: /etc/resolv.conf)
• Adds injector.networkDisruption.dnsNodeResolvConf config field (default: /mnt/host/etc/resolv.conf)
• Paths configurable via Helm values, ConfigMap, or CLI flags
• DNS client logs loaded resolv.conf paths and nameservers
• Changes DNS path handling from list-based to single path per context

Configuration example:

  injector:
    networkDisruption:
      dnsNodeResolvConf: "/mnt/host/run/systemd/resolve/resolv.conf"

Code Quality Checklist

• The documentation is up to date.
• My code is sufficiently commented and passes continuous integration checks.
• I have signed my commit (see Contributing Docs).

Testing

• I leveraged continuous integration testing
  • by depending on existing unit tests or end-to-end tests.
  • by adding new unit tests or end-to-end tests.
• I manually tested the following steps:
  • Verified default paths work correctly
  • Tested custom path configuration
  • Confirmed logging shows loaded paths
  • Validated CLI arguments passed to injector pods
  • locally.
  • as a canary deployment to a cluster.

[aymericDD]

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
Learn more

• [CHAOSPLT-1364] Fix cloud disruption hosts only injected in first chaos pod #1012
• [CHAOSPLT-259] Add percentage-based IP selection for network disruptions  #1011
• [CHAOSPLT-1360] Add DNS resolv.conf path customization for network disruptions #1010 👈 (View in Graphite)
• [CHAOSPLT-1359] Add DNS resolver control #1009
• main

This stack of pull requests is managed by Graphite. Learn more about stacking.

[datadog-datadog-prod-us1]

✅ Tests

🎉 All green!

❄️ No new flaky tests detected
🧪 All tests passed

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[diyarab]

The indentation looks a little off?