fix: cilium chaos duration should be optional

[grahambrereton-form3]

What problem does this PR solve?

What's changed and how it works?

Related changes

• This change also requires further updates to the website (e.g. docs)
• This change also requires further updates to the UI interface

Cherry-pick to release branches (optional)

This PR should be cherry-picked to the following release branches:

• release-2.6
• release-2.5

Checklist

CHANGELOG

Must include at least one of them.

• I have updated the CHANGELOG.md
• I have labeled this PR with "no-need-update-changelog"

Tests

Must include at least one of them.

• Unit test
• E2E test
• Manual test

Side effects

• Breaking backward compatibility

DCO

If you find the DCO check fails, please run commands like below (Depends on the actual situations. For example, if the failed commit isn't the most recent) to fix it:

git commit --amend --signoff
git push --force

[github-actions]

Created new release based on commit 8c22204

Release tag: v2.6.1-f3-8c222-cilium-chaos-duration

Link to release